Editing U.S. Route 101

{{Short description|U.S. Numbered Highway on the West Coast}}
{{Redirect|US 101|other uses|US-101 (disambiguation)}}
{{Use American English|date=April 2025}}
{{Featured article}}

{{Use mdy dates|date=April 2016}}
{{Infobox road
|country=USA
|type=US
|route=101
|map={{maplink-road|frame-height=290|from=U.S. Route 101.map}}
|map_custom=yes
|map_notes=US&nbsp;101 highlighted in red
|length_mi={{#expr:806.60+363.11+365.56}}
|length_round=0
|length_ref={{#tag:ref|Total length is calculated from route mileage within California ({{convert|806.597|mi|km|disp=comma}}),<!--Query results: Route 101 at Oregon line is postmile DN 46.489 and 806.597 on the statewide odometer--><ref name="CA-Postmile">{{cite web |author=California Department of Transportation |title=Postmile Services Query Tool |url=https://postmile.dot.ca.gov/PMQT/PostmileQueryTool.html |publisher=[[California Department of Transportation]] |accessdate=April 23, 2023 |archive-date=October 17, 2020 |url-status=live |archive-url=https://web.archive.org/web/20201017030520/https://postmile.dot.ca.gov/PMQT/PostmileQueryTool.html}}</ref> Oregon ({{convert|363.11|mi|km|disp=comma}}),<ref name="OR-Straightline">{{cite web |date=September 2015 |title=Straightline Charts: Oregon Coast Highway No. 9 |url=https://www.oregon.gov/odot/Data/Documents/SLC_Hwy009.pdf |publisher=[[Oregon Department of Transportation]] |url-status=dead |archive-url=https://web.archive.org/web/20230423225852/https://www.oregon.gov/odot/Data/Documents/SLC_Hwy009.pdf |archive-date=April 23, 2023 |accessdate=April 23, 2023}}</ref> and Washington ({{convert|365.56|mi|km|disp=comma}}).<ref name="WSDOT-log">{{WSDOT State Highway Log |year=2020 |pages=807–891 |link=yes |accessdate=April 23, 2023}}</ref>|group=lower-alpha|name=MP}}
|established={{start date|1926|11|11}}<ref name="USH">{{cite map |author1=[[Bureau of Public Roads]] |author2=[[American Association of State Highway Officials]] |date=November 11, 1926 |title=United States System of Highways Adopted for Uniform Marking by the American Association of State Highway Officials |url=https://commons.wikimedia.org/wiki/File:United_States_System_of_Highways_Adopted_for_Uniform_Marking_by_the_American_Association_of_State_Highway_Officials.jpg |scale=1:7,000,000 |location=Washington, DC |publisher=[[United States Geological Survey]] |oclc=32889555 |via=[[Wikimedia Commons]] |accessdate=November 7, 2013 |archive-date=April 13, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170413153913/https://commons.wikimedia.org/wiki/File:United_States_System_of_Highways_Adopted_for_Uniform_Marking_by_the_American_Association_of_State_Highway_Officials.jpg}}</ref>
|direction_a=South
|terminus_a={{Jct|country=USA|I|5|I|10|state=CA|SR|60}} in [[Los Angeles|Los Angeles, CA]]
|junction={{plainlist|1=
*{{Jct|country=USA|I|80}} in [[San Francisco|San Francisco, CA]]
*{{Jct|country=USA|US|199}} near [[Crescent City, California|Crescent City, CA]]
*{{Jct|country=USA|US|20}} in [[Newport, Oregon|Newport, OR]]
*{{Jct|country=USA|US|26}} near [[Seaside, Oregon|Seaside, OR]]
*{{Jct|country=USA|US|30}} in [[Astoria, Oregon|Astoria, OR]]
*{{Jct|country=USA|US|12}} in [[Aberdeen, Washington|Aberdeen, WA]]}}
|direction_b=North
|terminus_b={{Jct|country=USA|I|5}} in [[Tumwater, Washington|Tumwater, WA]]
|states=[[California]], [[Oregon]], [[Washington (state)|Washington]]
|previous_type=US
|previous_route=99
|next_type=US
|next_route=163
}}

'''U.S. Route 101''', or '''U.S. Highway 101''' ('''US&nbsp;101'''), is a major north–south highway that traverses the states of California, Oregon, and Washington on the [[West Coast of the United States]]. It is part of the [[United States Numbered Highway System]] and runs for over {{convert|1,500|mi|km}} along the [[Pacific Ocean]]. The highway is also known by various names, including [[El Camino Real (California)|El Camino Real]] in parts of California, the [[Oregon Coast Highway]], and the [[U.S. Route 101 in Washington|Olympic Highway]] in Washington. Despite its three-digit number, normally used for [[spur route]]s, US&nbsp;101 is classified as a primary route with 10 as its "first digit".

The highway's southern terminus is at a [[East Los Angeles Interchange|major interchange]] with [[Interstate 5]] (I-5) and [[Interstate 10|I-10]] in [[Los Angeles]]. US&nbsp;101 follows several freeways in [[Southern California]] as it travels north of the [[Santa Monica Mountains]] and along the coast, where it is [[Concurrency (road)|concurrent]] with [[California State Route 1]] (SR&nbsp;1). The highway travels inland from the coast after it splits from SR&nbsp;1 and approaches the [[San Francisco Bay Area]], where it becomes the [[Bayshore Freeway]] and later traverses [[San Francisco]] on city streets to reach the [[Golden Gate Bridge]]. US&nbsp;101 continues north on the [[Redwood Highway]] and rejoins the coast before it enters Oregon.

The Oregon Coast Highway carries US&nbsp;101 through the state's coastal towns and regions in the foothills of the [[Oregon Coast Range]]. The highway crosses over the [[Columbia River]] on the [[Astoria–Megler Bridge]] into Washington, where it follows [[Willapa Bay]] and an inland route to [[Aberdeen, Washington|Aberdeen]] and [[Olympic National Park]]. US&nbsp;101 travels north and east around the [[Olympic Peninsula]] and reaches its northernmost point in [[Port Angeles, Washington|Port Angeles]]; from there, it travels east and later south to its northern terminus at I-5 in [[Tumwater, Washington|Tumwater]], near [[Olympia, Washington|Olympia]]. Several portions of the highway are also designated as [[scenic byway]]s, including the Pacific Coast Scenic Byway in Washington; US&nbsp;101 also serves three [[List of national parks of the United States|national parks]]: [[Pinnacles National Park|Pinnacles]], [[Redwood National Park|Redwood]], and Olympic.

The highway is a major north–south link along the [[Pacific coast]] north of San Francisco but does not serve the largest cities in Oregon and Washington; that role is instead filled by I-5, which has a more direct inland routing. US&nbsp;101 was established in 1926 and followed several historic routes, including El Camino Real, which linked California's early [[Spanish missions in California|Spanish missions]], pueblos, and [[presidio]]s. It originally terminated to the south in [[San Diego]] but was truncated to Los Angeles in 1964 after the construction of I-5. Other sections were later moved to freeway alignments that bypassed cities. Several sections of US&nbsp;101 in Washington and Oregon were rebuilt in the mid-20th century to eliminate curves and address traffic congestion. Later projects expanded the Bayshore Freeway in the San Francisco Bay Area and relocated sections of the highway in Oregon in response to landslides and erosion.

==Route description==
{{lengths table}}
|-
! scope="row" style="text-align:center;" | [[U.S. Route 101 in California|{{abbr|CA|California}}]]<ref name="CA-Postmile"/>
|{{convert|806.60|mi|km|disp=table}}
|-
! scope="row" style="text-align:center;" | [[U.S. Route 101 in Oregon|{{abbr|OR|Oregon}}]]<ref name="OR-Straightline"/>
|{{convert|363.11|mi|km|disp=table}}
|-
! scope="row" style="text-align:center;" | [[U.S. Route 101 in Washington|{{abbr|WA|Washington}}]]<ref name="WSDOT-log"/>
|{{convert|365.56|mi|km|disp=table}}
|-
! scope="row" style="text-align:center;" | Total
|{{convert|{{#expr:806.60+363.11+365.56}}|mi|km|disp=table}}
|}

US&nbsp;101 is a major highway that generally follows the [[Pacific Ocean]] through the [[West Coast of the United States|West Coast]] states of [[California]], [[Oregon]], and [[Washington (state)|Washington]]. It spans over {{convert|1,500|mi|km}} from its southern terminus in [[Los Angeles]] to its northern terminus near [[Olympia, Washington]].<ref name="Mercury">{{cite news |last=Wigglesworth |first=Zeke |date=August 22, 1993 |title=Olympic Games: Old-growth forests, glacial peaks, hot springs...We have the British to thank for a peninsula with some of the most varied scenery anywhere |page=1G |work=[[The Mercury News]]}}</ref><ref>{{cite news |date=December 5, 2019 |title=This is America's most iconic road trip |url=https://www.mensjournal.com/travel/americas-iconic-road-trip |work=[[Men's Journal]] |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730063002/https://www.mensjournal.com/travel/americas-iconic-road-trip}}</ref> US&nbsp;101 generally runs parallel to [[Interstate 5|I-5]], which serves most of the West Coast's largest cities and is designated for long-haul freight.<ref name="OPB-Riprap">{{cite news |last=Foden-Vencil |first=Kristian |date=February 1, 2022 |title=Oregon tries to tweak land-use rules to save Highway 101 |url=https://www.opb.org/article/2022/02/01/oregon-land-use-rules-prevent-repair-highway-101-erosion-rip-rap/ |publisher=[[Oregon Public Broadcasting]] |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730064856/https://www.opb.org/article/2022/02/01/oregon-land-use-rules-prevent-repair-highway-101-erosion-rip-rap/}}</ref><ref>{{cite map |date=March 14, 2023 |title=National Highway Freight Network Map |url=https://ops.fhwa.dot.gov/freight/infrastructure/nfn/maps/nhfn_map.htm |publisher=[[Federal Highway Administration]] |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730064856/https://ops.fhwa.dot.gov/freight/infrastructure/nfn/maps/nhfn_map.htm}}</ref> The corridor is also designated as part of [[U.S. Bicycle Route 95]] (USBR&nbsp;95) in [[Northern California]] and is proposed to be part of [[U.S. Bicycle Route 40|USBR&nbsp;40]] and [[U.S. Bicycle Route 97|USBR&nbsp;97]] in Washington.<ref>{{cite web |title=USBRS Maps and Route Resources |date=October 12, 2015 |url=https://www.adventurecycling.org/routes-and-maps/us-bicycle-route-system/maps-and-route-resources/ |publisher=[[Adventure Cycling Association]] |accessdate=July 29, 2023 |archive-date=August 11, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230811220312/https://www.adventurecycling.org/routes-and-maps/us-bicycle-route-system/maps-and-route-resources/}}</ref><ref>{{cite map |title=United States Bicycle Route System (USBRS): Existing and Proposed Routes in Washington State |url=https://wsdot.wa.gov/sites/default/files/2021-12/USBRS-Concept-Map.pdf |publisher=Washington State Department of Transportation |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730063437/https://wsdot.wa.gov/sites/default/files/2021-12/USBRS-Concept-Map.pdf}}</ref>

The highway is known by several names that vary between the states. In California, portions of US&nbsp;101 are part of the [[Santa Ana Freeway]], [[Hollywood Freeway]], [[Ventura Freeway]], [[Bayshore Freeway]], and [[Redwood Highway]].<ref name="CA-Names">{{cite web |author=Caltrans Division of Research, Innovation and System Information |date=January 2022 |title=2021 Named Freeways, Highways, Structures, and Other Appurtenances in California |pages=61–72, 102–103 |url=https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/place-names/web-2021-named-freeways-final-a11y.pdf |publisher=California Department of Transportation |accessdate=July 27, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728051828/https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/place-names/web-2021-named-freeways-final-a11y.pdf}}</ref> In Oregon, it is officially the Oregon Coast Highway No. 9 under the [[List of named state highways in Oregon|named highways system]] and part of the Pacific Coast Scenic Byway, a [[National Scenic Byway]].<ref>{{cite web |title=2020 Cross Reference Table of Highway Route Number to State Highway Number |url=https://www.oregon.gov/odot/Data/Documents/Routes-to-Highway-Cross-Reference-Table.pdf |publisher=Oregon Department of Transportation |accessdate=July 29, 2023 |archive-date=July 24, 2020 |url-status=live |archive-url=https://web.archive.org/web/20200724080113/https://www.oregon.gov/odot/Data/Documents/Routes-to-Highway-Cross-Reference-Table.pdf}}</ref><ref>{{cite web |title=National Scenic Byways & All-American Roads: Oregon (OR) |url=https://fhwaapps.fhwa.dot.gov/bywaysp/States/Show/OR |publisher=Federal Highway Administration |accessdate=July 29, 2023 |archive-date=September 25, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230925123458/https://fhwaapps.fhwa.dot.gov/bywaysp/States/Show/OR}}</ref> In Washington, it is officially part of the Pacific Coast Scenic Byway, a [[Washington State Scenic and Recreational Highways|state scenic highway]].<ref>{{cite web |year=2018 |title=Washington State's Scenic Byways & Road Trips |pages=68–71 |url=https://wsdot.wa.gov/sites/default/files/2018/07/17/scenic-byways-travel-planner.pdf |publisher=Washington State Department of Transportation |url-status=dead |archive-url=https://web.archive.org/web/20211022060522/https://wsdot.wa.gov/sites/default/files/2018/07/17/scenic-byways-travel-planner.pdf |archive-date=October 22, 2021 |accessdate=July 29, 2023}}</ref> In [[Southern California]], US&nbsp;101 is commonly called "the 101" (pronounced "the one oh one").<ref>{{cite news |last=Masters |first=Nathan |date=November 10, 2015 |title=The 5, the 101, the 405: Why Southern Californians Love Saying 'the' Before Freeway Numbers |url=https://www.kcet.org/shows/lost-la/the-5-the-101-the-405-why-southern-californians-love-saying-the-before-freeway-numbers |publisher=[[KCET]] |accessdate=August 4, 2017 |archive-date=August 20, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160820000300/https://www.kcet.org/shows/lost-la/the-5-the-101-the-405-why-southern-californians-love-saying-the-before-freeway-numbers}}</ref>

===California===
{{Main|U.S. Route 101 in California}}
[[File:Highway 101 at night in Los Angeles.jpg|thumb|upright=0.666|US 101 on the [[Hollywood Freeway]] with [[Downtown Los Angeles]] in the background|alt=Aerial photograph of a freeway at night with car traffic turned into light trails with a long exposure; the skyline of Downtown Los Angeles is seen in the background.]]

US&nbsp;101 travels on several major freeways in the [[Greater Los Angeles area]], including some of the most congested roads in the United States.<ref>{{cite web |author=((FHWA Office of Highway Policy)) |year=2021 |title=The 25 Most Traveled Route Locations by Annual Average Daily Traffic (AADT) |url=https://www.fhwa.dot.gov/policyinformation/tables/02.pdf |publisher=Federal Highway Administration |accessdate=July 27, 2023 |archive-date=August 10, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230810193630/https://www.fhwa.dot.gov/policyinformation/tables/02.pdf}}</ref><ref>{{cite news |last=Nelson |first=Laura J. |date=March 15, 2016 |title=Los Angeles area can claim the worst traffic in America. Again |url=https://www.latimes.com/local/lanow/la-me-ln-la-worst-traffic-20160314-story.html |work=[[Los Angeles Times]] |accessdate=July 27, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728051828/https://www.latimes.com/local/lanow/la-me-ln-la-worst-traffic-20160314-story.html}}</ref> Its southern terminus is in [[Boyle Heights, Los Angeles|Boyle Heights]] at the {{convert|135|acre|ha|adj=mid}} [[East Los Angeles Interchange]], one of the busiest freeway junctions in the United States, where US&nbsp;101 meets I-5, [[Interstate 10|I-10]], and [[California State Route 60|SR&nbsp;60]].<ref>{{cite news |last1=Dillon |first1=Liam |last2=Poston |first2=Ben |date=November 11, 2021 |title=The racist history of America's interstate highway boom |url=https://www.latimes.com/homeless-housing/story/2021-11-11/the-racist-history-of-americas-interstate-highway-boom |work=Los Angeles Times |accessdate=July 27, 2023 |archive-date=July 27, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230727020848/https://www.latimes.com/homeless-housing/story/2021-11-11/the-racist-history-of-americas-interstate-highway-boom}}</ref><ref>{{cite news |last1=Gamboa |first1=Suzanne |last2=McCausland |first2=Phil |last3=Lederman |first3=Josh |last4=Popken |first4=Ben |date=June 18, 2021 |title=Bulldozed and bisected: Highway construction built a legacy of inequality |url=https://www.nbcnews.com/specials/america-highways-inequality/ |publisher=[[NBC News]] |accessdate=July 27, 2023 |archive-date=June 24, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230624054418/https://www.nbcnews.com/specials/america-highways-inequality/}}</ref> The highway travels north on a section of the Santa Ana Freeway and turns west to cross the [[Los Angeles River]] after merging with the [[San Bernardino Freeway]].<ref name="CA-Names"/> The Santa Ana Freeway continues across [[Downtown Los Angeles]] and passes [[Union Station (Los Angeles)|Union Station]], a major transit hub, and government buildings before it reaches a junction with [[California State Route 110|SR&nbsp;110]]. Beyond Downtown Los Angeles, US&nbsp;101 uses the Hollywood Freeway as it travels northwest through the [[Hollywood, Los Angeles|eponymous neighborhood]] towards [[Cahuenga Pass]], where it crosses the [[Hollywood Hills]] and passes [[Universal Studios Hollywood]].<ref name="LATimes-Cahuenga">{{cite news |last=Simon |first=Richard |date=December 19, 1994 |title=Hollywood Freeway spans magic and might of L.A. |page=A1 |url=https://www.latimes.com/archives/la-xpm-1994-12-19-mn-10830-story.html |work=Los Angeles Times |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729032021/https://www.latimes.com/archives/la-xpm-1994-12-19-mn-10830-story.html}}</ref> The highway leaves the Hollywood Freeway to turn west onto the Ventura Freeway, which travels along the southern edge of the suburban [[San Fernando Valley]] and intersects [[Interstate 405 (California)|I-405]]. US&nbsp;101 continues into [[Ventura County, California|Ventura County]], where it joins [[California State Route 1|SR&nbsp;1]] and serves communities in the [[Conejo Valley]] and [[Oxnard Plain]].<ref name="google">{{google maps |title=U.S. Route 101 |url=https://www.google.com/maps/dir/34.0289832,-118.2139833/47.0212782,-122.9062948/@40.60196,-131.9325751,3476338m/am=t/data=!3m2!1e3!4b1!4m44!4m43!1m40!3m4!1m2!1d-120.306674!2d34.7703559!3s0x80ec050b5f1c2a1b:0x8db5b9367d4922a!3m4!1m2!1d-122.0784263!2d37.4122168!3s0x808fb7515aece6b5:0xa11d2332b0d5a66!3m4!1m2!1d-122.4406874!2d37.7993101!3s0x808580d6ae5e4089:0xe331014beb67bd6a!3m4!1m2!1d-124.3984596!2d42.2566154!3s0x54dab89732730c53:0x3c794b0c929c2dc1!3m4!1m2!1d-124.0394112!2d44.8584946!3s0x54ea88effd596fe7:0x4847f63f9fd25649!3m4!1m2!1d-124.052869!2d46.3219217!3s0x54936d73ad238135:0x8e193f32a334ca73!3m4!1m2!1d-124.2283092!2d48.0651861!3s0x548e8aa5f56cbe37:0xda64e09042649688!3m4!1m2!1d-123.1315677!2d47.4177499!3s0x5491c6e8d1ae8489:0x5ef4ce81cf98b0e5!1m0!3e0?entry=ttu |accessdate=July 27, 2023}}</ref>

The highway follows the Pacific Ocean northwest from [[Ventura, California|Ventura]] through [[Santa Barbara, California|Santa Barbara]], where it separates the downtown from its beach, and [[Goleta, California|Goleta]]. US&nbsp;101 becomes a [[divided highway]] beyond Goleta as it turns north at [[Gaviota State Park]] to cross the [[Santa Ynez Mountains]] at [[Gaviota Pass]]; SR&nbsp;1 splits to remain closer to the coastline, as it does in several areas of the state. The highway continues inland and travels around the [[Purisima Hills]] to reach [[Santa Maria, California|Santa Maria]], where the freeway resumes as it bypasses the city. US&nbsp;101 briefly returns to the coastline near [[Pismo Beach, California|Pismo Beach]] and turns inland over the [[Irish Hills (California)|Irish Hills]] towards [[San Luis Obispo, California|San Luis Obispo]] alongside SR&nbsp;1.<ref name="google"/> The highway crosses the [[Santa Lucia Range]] through [[Cuesta Pass]] and follows the [[Salinas River (California)|Salinas River]] northwest through [[Atascadero, California|Atascadero]] and the wine-growing region surrounding [[Paso Robles, California|Paso Robles]].<ref>{{cite news |last=Stone |first=Robert |date=March 7, 1993 |title=California's secret heart |at=sec. 6, p. 22 |url=https://www.nytimes.com/1993/03/07/magazine/california-s-secret-heart.html |work=[[The New York Times]] |accessdate=July 27, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728065055/https://www.nytimes.com/1993/03/07/magazine/california-s-secret-heart.html}}</ref> US&nbsp;101 passes near [[Pinnacles National Park]] and travels through the city of [[Salinas, California|Salinas]], where it turns northeast to cross the [[Gabilan Range]].<ref>{{cite news |last=Reynolds |first=Christopher |date=February 10, 2022 |title=Why are so many people heading to California's newest national park? |url=https://www.latimes.com/travel/story/2022-02-10/where-is-pinnacles-national-park-and-why-are-so-many-people-going-there |work=Los Angeles Times |accessdate=July 27, 2023 |archive-date=July 26, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230726215134/https://www.latimes.com/travel/story/2022-02-10/where-is-pinnacles-national-park-and-why-are-so-many-people-going-there}}</ref> From there, the highway descends into the [[Santa Clara Valley]] and [[Gilroy, California|Gilroy]], the southernmost city in the [[San Francisco Bay Area]].<ref name="google"/><ref>{{cite news |last=Murphy |first=Katy |date=May 1, 2017 |title=As California grows, Menlo Park and other Bay Area cities see population boom |url=https://www.mercurynews.com/2017/05/01/as-california-grows-menlo-park-and-other-bay-area-cities-see-population-boom/ |work=The Mercury News |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075939/https://www.mercurynews.com/2017/05/01/as-california-grows-menlo-park-and-other-bay-area-cities-see-population-boom/}}</ref>

US&nbsp;101 continues northwest into [[San Jose, California|San Jose]] on the South Valley Freeway and later the Bayshore Freeway, which travels around the east and north sides of downtown San Jose. The ten-lane freeway generally follows the west side of [[San Francisco Bay]] as it traverses several [[Silicon Valley]] communities, including [[Palo Alto, California|Palo Alto]], [[Redwood City, California|Redwood City]], and [[San Mateo, California|San Mateo]], and passes offices for high-tech companies.<ref name="SPUR-Bayshore">{{cite web |last1=Amin |first1=Ratna |last2=Pugh |first2=Graham |date=October 28, 2015 |title=Will rail rule the Bay Area Peninsula corridor again? |url=https://www.spur.org/news/2015-10-28/will-rail-rule-bay-area-peninsula-corridor-again |publisher=[[SPUR (San Francisco organization)|SPUR]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075938/https://www.spur.org/news/2015-10-28/will-rail-rule-bay-area-peninsula-corridor-again}}</ref><ref>{{cite news |last=Budman |first=Scott |date=August 4, 2009 |title=Highway 101: The tech industry's Madison Avenue |url=https://www.nbcbayarea.com/news/local/the-tech-industrys-madison-avenue/1842759/ |publisher=[[KNTV|NBC Bay Area]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075937/https://www.nbcbayarea.com/news/local/the-tech-industrys-madison-avenue/1842759/}}</ref> It parallels [[Interstate 280 (California)|I-280]], which travels along the foothills of the [[Santa Cruz Mountains]] to the west, as the two continue up the [[San Francisco Peninsula]].<ref>{{cite news |last=Egusa |first=Christopher |date=February 6, 2020 |title=Why does Highway 101 have so many billboards and 280 has almost none? |url=https://www.kalw.org/show/crosscurrents/2020-02-06/why-does-highway-101-have-so-many-billboards-and-280-has-almost-none |publisher=[[KALW]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075936/https://www.kalw.org/show/crosscurrents/2020-02-06/why-does-highway-101-have-so-many-billboards-and-280-has-almost-none}}</ref> US&nbsp;101 passes [[San Francisco International Airport]] and briefly turns northeast to rejoin the coastline before it enters the city of San Francisco near [[Candlestick Point]]. The Bayshore Freeway intersects I-280 and terminates at an interchange with [[Interstate 80|I-80]] near the [[South of Market, San Francisco|SoMa]] neighborhood in the city center.<ref name="google"/> US&nbsp;101 then uses city streets to continue through San Francisco; it travels north on [[Van Ness Avenue]], a wide boulevard with [[bus lane]]s, and west on [[Lombard Street (San Francisco)|Lombard Street]] to the [[Presidio of San Francisco]], a historic landmark and city park.<ref>{{cite news |last=Nolte |first=Carl |date=June 30, 2018 |title=Streets of San Francisco are always being dug up |url=https://www.sfchronicle.com/bayarea/nativeson/article/Streets-of-San-Francisco-are-always-being-dug-up-13039269.php |work=[[San Francisco Chronicle]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075939/https://www.sfchronicle.com/bayarea/nativeson/article/Streets-of-San-Francisco-are-always-being-dug-up-13039269.php}}</ref><ref>{{cite report |last1=Bunse |first1=Meta |last2=Allen |first2=Polly |date=December 2009 |title=Van Ness Avenue Bus Rapid Transit (BRT) Project: Historic Resources Inventory and Evaluation Report |pages=29–32 |url=https://www.sfcta.org/sites/default/files/content/Planning/VanNess_BRT_EIR/FEIR-FEIS/Tech%20Memos/Cultural%20Resources%20Reports/Historic%20Resources%20Evaluation%20and%20Inventory%20Report/Final_HRIER_Van_Ness_December%202009.pdf |publisher=[[San Francisco County Transportation Authority]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075937/https://www.sfcta.org/sites/default/files/content/Planning/VanNess_BRT_EIR/FEIR-FEIS/Tech%20Memos/Cultural%20Resources%20Reports/Historic%20Resources%20Evaluation%20and%20Inventory%20Report/Final_HRIER_Van_Ness_December%202009.pdf}}</ref>

[[File:Golden Gate Bridge as seen from Marshall's Beach, March 2018.jpg|thumb|left|The [[Golden Gate Bridge]] connects sections of US&nbsp;101 between [[San Francisco]] and [[Marin County, California|Marin County]].|alt=The Golden Gate Bridge, a two-tower suspension bridge painted a dull orange, seen on a sunny day from a beach with mist over the water.]]

The divided highway travels through the north side of the Presidio and tunnels under a portion of the park as it approaches the [[Golden Gate Bridge]],<ref>{{cite news |last=King |first=John |date=July 16, 2022 |title=S.F.'s Tunnel Tops park is open. But it might not be the best new park at the Presidio |url=https://www.sfchronicle.com/sf/article/presidio-park-tunnel-tops-open-17308693.php |work=San Francisco Chronicle |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075937/https://www.sfchronicle.com/sf/article/presidio-park-tunnel-tops-open-17308693.php}}</ref> a [[toll bridge|tolled]] [[suspension bridge]] across the [[Golden Gate]] at the entrance to San Francisco Bay.<ref>{{cite news |last=Swan |first=Rachel |date=December 18, 2018 |title=Golden Gate Bridge toll may climb near $10 by 2023 |url=https://www.sfchronicle.com/bayarea/article/Golden-Gate-Bridge-toll-may-climb-near-10-by-2023-13476526.php |work=San Francisco Chronicle |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075939/https://www.sfchronicle.com/bayarea/article/Golden-Gate-Bridge-toll-may-climb-near-10-by-2023-13476526.php}}</ref><ref name="NPR-Bridge">{{cite news |last=Stamberg |first=Susan |date=April 26, 2011 |title=The Golden Gate Bridge's accidental color |url=https://www.npr.org/2011/04/26/135150942/the-golden-gate-bridges-accidental-color |work=[[Morning Edition]] |publisher=[[NPR]] |accessdate=July 28, 2023 |archive-date=May 24, 2019 |url-status=live |archive-url=https://web.archive.org/web/20190524000236/https://www.npr.org/2011/04/26/135150942/the-golden-gate-bridges-accidental-color}}</ref> It is operated by the [[Golden Gate Bridge, Highway and Transportation District]] and is not legally defined as part of US&nbsp;101 and SR&nbsp;1.<ref>{{cite web |title=FAQs |url=https://www.goldengate.org/bridge/history-research/statistics-data/faqs/ |publisher=[[Golden Gate Bridge, Highway and Transportation District]] |accessdate=April 24, 2024}}</ref> The orange-colored bridge, considered an icon of the city,<ref name="NPR-Bridge"/> has six lanes with a [[reversible lane|movable barrier]] and walkways on both sides for pedestrians and cyclists.<ref>{{cite news |date=January 11, 2015 |title=Golden Gate Bridge closes for safety improvements |url=https://www.usatoday.com/story/news/nation/2015/01/11/gaolden-gate-bridge-closure/21589661/ |work=[[USA Today]] |agency=[[Associated Press]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728075936/https://www.usatoday.com/story/news/nation/2015/01/11/gaolden-gate-bridge-closure/21589661/}}</ref> North of the bridge, US&nbsp;101 is designated as the Redwood Highway.<ref name="CA-Names"/> It splits from SR&nbsp;1 and continues as an eight-lane freeway through suburban communities in [[Marin County, California|Marin County]], including an elevated viaduct in downtown [[San Rafael, California|San Rafael]].<ref>{{cite news |last=Graff |first=Amy |date=July 7, 2022 |title=Major closure coming to Highway 101 in Marin, delays up to 1 hour expected |url=https://www.sfgate.com/bayarea/article/highway-101-marin-lanes-closing-17288546.php |work=[[SFGate]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728082149/https://www.sfgate.com/bayarea/article/highway-101-marin-lanes-closing-17288546.php}}</ref><ref>{{cite news |last=Harrison |first=Robert L. |date=September 14, 2020 |title=Super-highway on viaduct to break San Rafael bottleneck |url=https://medium.com/anne-t-kent-california-room-community-newsletter/super-highway-on-viaduct-to-break-san-rafael-bottleneck-3006dd4482e |publisher=Anne T. Kent California Room at [[Marin County Free Library]] |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728082149/https://medium.com/anne-t-kent-california-room-community-newsletter/super-highway-on-viaduct-to-break-san-rafael-bottleneck-3006dd4482e}}</ref> The highway continues along the west side of [[San Pablo Bay]] into [[Sonoma County, California|Sonoma County]], where it turns northwest to head inland through [[Petaluma, California|Petaluma]] and [[Santa Rosa, California|Santa Rosa]] in the [[North Bay (San Francisco Bay Area)|North Bay]]'s [[Wine Country]].<ref>{{cite news |last=Sachs |first=Andrea |date=February 16, 2018 |title=After the October wildfires, California Wine Country is ready to pop some corks |url=https://www.washingtonpost.com/lifestyle/travel/after-the-october-wildfires-california-wine-country-is-ready-to-pop-some-corks/2018/02/15/9b17cf26-0c2f-11e8-8890-372e2047c935_story.html |newspaper=[[The Washington Post]] |accessdate=July 28, 2023 |archive-date=November 27, 2020 |url-status=live |archive-url=https://web.archive.org/web/20201127072036/https://www.washingtonpost.com/lifestyle/travel/after-the-october-wildfires-california-wine-country-is-ready-to-pop-some-corks/2018/02/15/9b17cf26-0c2f-11e8-8890-372e2047c935_story.html}}</ref><ref>{{cite news |last=Swan |first=Rachel |date=August 25, 2019 |title=North Bay's SMART train, beloved but not bustling, looks to extend sales tax |url=https://www.sfchronicle.com/bayarea/article/North-Bay-s-SMART-train-beloved-but-not-14376250.php |work=San Francisco Chronicle |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728082149/https://www.sfchronicle.com/bayarea/article/North-Bay-s-SMART-train-beloved-but-not-14376250.php}}</ref> US&nbsp;101 follows the [[Russian River (California)|Russian River]] upstream through wineries and vineyards into [[Mendocino County, California|Mendocino County]] as the freeway narrows to four lanes and eventually ends.<ref name="google"/>

Beyond the San Francisco Bay Area, US&nbsp;101 is primarily an undivided highway with some short freeway sections and serves as the primary route in the rugged [[North Coast (California)|North Coast]] region.<ref>{{cite news |last=Riley |first=Frank |date=July 14, 1985 |title=Adventure awaits visitors on the Redwood Trail |url=https://www.latimes.com/archives/la-xpm-1985-07-14-tr-6575-story.html |work=Los Angeles Times |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728085943/https://www.latimes.com/archives/la-xpm-1985-07-14-tr-6575-story.html}}</ref> It traverses the [[Mendocino Range]] and reaches the northern terminus of SR&nbsp;1 at [[Leggett, California|Leggett]].<ref>{{cite news |last=Wall |first=Jonathan |date=May 2, 2004 |title=Long and winding road |page=50 |work=[[South China Morning Post]]}}</ref> The Redwood Highway then follows the [[South Fork Eel River]] north into [[Humboldt Redwoods State Park]], where it runs parallel to the [[Avenue of the Giants]].<ref>{{cite news |last=Steigerwald |first=Bill |date=October 31, 2010 |title=Travels without Charley: Riding the Oregon-California coast truly mesmerizing |page=E5 |url=https://www.post-gazette.com/life/travel/2010/10/31/Travels-Without-Charley-Riding-the-Oregon-California-coast-truly-mesmerizing/stories/201010310301 |work=[[Pittsburgh Post-Gazette]] |url-access=subscription |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728085943/https://www.post-gazette.com/life/travel/2010/10/31/Travels-Without-Charley-Riding-the-Oregon-California-coast-truly-mesmerizing/stories/201010310301}}</ref> US&nbsp;101 continues northwest along the [[Eel River (California)|Eel River]] to reach the coastline near [[Eureka, California|Eureka]], which it travels through on city streets before becoming a divided highway around [[Humboldt Bay]]. The highway travels north along the coast through the [[Redwood National and State Parks]], where it passes through old-growth [[coast redwood]] forests, and reaches [[Crescent City, California|Crescent City]].<ref>{{cite news |last=Dixon |first=Chris |date=April 29, 2005 |title=A coast less traveled |page=F1 |url=https://www.nytimes.com/2005/04/29/travel/escapes/a-coast-less-traveled.html |work=The New York Times |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728085943/https://www.nytimes.com/2005/04/29/travel/escapes/a-coast-less-traveled.html}}</ref> US&nbsp;101 intersects [[U.S. Route 199|US&nbsp;199]] north of the city and continues northwest along the coast to the Oregon state line.<ref name="google"/>

===Oregon===
{{Main|U.S. Route 101 in Oregon}}
[[File:Beach north of Cape Sebastian.jpg|thumb|right|A coastline section of US&nbsp;101 near [[Cape Sebastian]]|alt=A view from the shoulder of a highway of several large rock outcroppings on a coastal beach with small trees and grasses in the foreground.]]

The Oregon Coast Highway begins at the California state line near [[Brookings, Oregon|Brookings]] and carries US&nbsp;101 north along the Pacific coast. It is generally a two-lane highway that passes through small towns and near 77 [[List of Oregon state parks|state parks]] on the rugged coastline, as well as some inland areas.<ref name="AAA-Trip">{{cite news |last=Anderson |first=Bruce |date=March 1, 2019 |title=Highway 101: The ultimate West Coast drive |url=https://mwg.aaa.com/via/road-trips/highway-101-west-coast-drive |work=Via |publisher=[[AAA Northern California, Nevada & Utah]] |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729051719/https://mwg.aaa.com/via/road-trips/highway-101-west-coast-drive}}</ref><ref>{{cite book |last1=Merriam, Jr. |first1=Lawrence C. |last2=Talbot |first2=David G. |year=1992 |title=Oregon's Highway Park System, 1921–1989: An Administrative History, Including Historical Overview and Park Directory |chapter=Directory of Oregon State Park Areas |chapter-url=http://npshistory.com/publications/oregon/admin_history/directory.htm |publisher=[[Oregon Parks and Recreation Department]] |location=Salem, Oregon |oclc=28184451 |via=NPS History Electronic Library & Archive |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729051710/http://npshistory.com/publications/oregon/admin_history/directory.htm}}</ref> From Brookings, US&nbsp;101 traverses the {{convert|12|mi|km|adj=mid}} [[Samuel H. Boardman State Scenic Corridor]], which includes roadside viewpoints and trailheads that face the ocean.<ref>{{cite news |last=Hale |first=Jamie |date=February 12, 2017 |title=The most scenic stretch of the Oregon coast: Touring beautiful Boardman state park |url=https://www.oregonlive.com/travel/2017/02/the_most_scenic_stretch_of_the.html |work=[[The Oregonian]] |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729051707/https://www.oregonlive.com/travel/2017/02/the_most_scenic_stretch_of_the.html}}</ref> The highway remains elevated from the coastline and briefly descends to [[sea level]] near the [[Pistol River State Scenic Viewpoint]] before climbing [[Cape Sebastian]] on its way to [[Gold Beach, Oregon|Gold Beach]]. US&nbsp;101 travels through Gold Beach and crosses the [[Rogue River (Oregon)|Rogue River]] to continue north along the coast.<ref name="google"/> The highway turns west to follow the base of [[Humbug Mountain]], a {{convert|1,761|ft|m|adj=mid}} mountain that rises from the Pacific Ocean,<ref>{{cite news |last=Urness |first=Zach |date=May 2, 2016 |title=The joy of disappointment on Humbug Mountain |url=https://www.statesmanjournal.com/story/travel/outdoors/2016/05/03/humbug-mountain-state-park-trail-oregon-coast/83830398/ |work=[[Statesman Journal]] |accessdate=July 28, 2023 |archive-date=March 16, 2024 |url-status=live |archive-url=https://web.archive.org/web/20240316074054/https://www.statesmanjournal.com/story/travel/outdoors/2016/05/03/humbug-mountain-state-park-trail-oregon-coast/83830398/}}</ref> and northwest to reach [[Port Orford, Oregon|Port Orford]], where it leaves the coastline.<ref name="OR-Map">{{cite map |date=April 2023 |title=Oregon Official State Map |url=https://www.oregon.gov/odot/Data/Documents/Map_Official_State_Front.pdf |at=[https://www.oregon.gov/odot/Data/Documents/Map_Official_State_Back.pdf Astoria and Coos Bay–North Bend] insets |publisher=Oregon Department of Transportation |accessdate=July 28, 2023 |archive-date=July 17, 2020 |url-status=live |archive-url=https://web.archive.org/web/20200717135748/https://www.oregon.gov/odot/Data/Documents/Map_Official_State_Front.pdf}}</ref><ref name="ODOT-Context">{{cite report |last1=Gratreak |first1=Leesa |last2=Stuart |first2=Patience |last3=Jones |first3=Shoshana |last4=Becker |first4=Anisa |editor-last=Ranzetta |editor-first=Kirk |date=February 2, 2015 |title=US 101 Coast Highway Historic Context |page=22 |url=https://www.oregon.gov/odot/GeoEnvironmental/Docs_CulturalResource/US_101-Historic_Context.pdf |publisher=[[AECOM]] |via=Oregon Department of Transportation |accessdate=July 26, 2023 |archive-date=July 27, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230727042755/https://www.oregon.gov/odot/GeoEnvironmental/Docs_CulturalResource/US_101-Historic_Context.pdf}}</ref>

US&nbsp;101 continues north, separated from the coastline by prairies and marshes, to [[Bandon, Oregon|Bandon]]; there, it briefly turns east and crosses the [[Coquille River (Oregon)|Coquille River]] to traverse more marshes.<ref>{{cite news |last=Muldoon |first=Katy |date=June 29, 2010 |title=The once and future marsh: In Bandon, Oregon, a salt marsh is re-engineered |url=https://www.oregonlive.com/environment/2010/06/the_once_and_future_marsh_in_b.html |work=The Oregonian |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729051708/https://www.oregonlive.com/environment/2010/06/the_once_and_future_marsh_in_b.html}}</ref> The highway travels further inland to the northeast and follows a slough off [[Coos Bay]] to the neighboring cities of [[Coos Bay, Oregon|Coos Bay]] and [[North Bend, Oregon|North Bend]], where it splits into a pair of [[one-way pair|one-way streets]].{{sfnp|Gratreak|Stuart|Jones|Becker|2015|p=20}} US&nbsp;101 leaves North Bend and crosses Coos Bay on the [[Conde McCullough Memorial Bridge]]; from there, it heads north along the edge of a {{convert|40|mi|km|adj=mid}} exposed [[coastal dune|coastal sand dune]] that forms the [[Oregon Dunes National Recreation Area]], along with freshwater lakes to the east.<ref>{{cite news |last=Richard |first=Terry |date=April 6, 2003 |title=Northwest Outdoors — Umpqua Dunes: Highest, widest in Oregon |page=T7 |url=https://www.oregonlive.com/terryrichard/2007/07/umpqua_dunes.html |work=The Oregonian |url-status=dead |archive-url=https://web.archive.org/web/20210420003038/https://www.oregonlive.com/terryrichard/2007/07/umpqua_dunes.html |archive-date=April 20, 2021 |accessdate=July 28, 2023}}</ref><ref>{{cite news |last=Tizon |first=Alex |author-link=Alex Tizon |date=November 17, 1999 |title=Dune Buggy: Here's a spectacular playground |url=https://archive.seattletimes.com/archive/?date=19991117&slug=2995781 |work=[[The Seattle Times]] |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729051709/https://archive.seattletimes.com/archive/?date=19991117&slug=2995781}}</ref> US&nbsp;101 diverts northeast to cross the [[Umpqua River]] at [[Reedsport, Oregon|Reedsport]] and passes through a meandering section near [[Tahkenitch Lake]] before it returns to the coastal dunes around [[Dunes City, Oregon|Dunes City]].<ref name="google"/><ref name="OR-Map"/>

The Oregon Coast Highway crosses the [[Siuslaw River]] into [[Florence, Oregon|Florence]] and intersects [[Oregon Route 126]] (OR&nbsp;126), a major east–west route that traverses the [[Oregon Coast Range|Coast Range]] to [[Eugene, Oregon|Eugene]].<ref name="OR-Map"/> US&nbsp;101 returns to the coastline near the [[Heceta Head Lighthouse]] and continues north along several high cliffs around [[Cape Perpetua]] and [[Yachats, Oregon|Yachats]] that overlook the beaches.<ref>{{cite news |last=Yenckel |first=James T. |date=May 24, 1987 |title=The coast |url=https://www.washingtonpost.com/archive/lifestyle/travel/1987/05/24/the-coast/5b926ce7-2815-48be-8a0b-22e482fdc55a/ |newspaper=The Washington Post |accessdate=July 28, 2023}}</ref><ref name="CNTraveler">{{cite news |last=Moss |first=Tyler |date=May 2, 2016 |title=The Oregon Coast: The U.S. road trip as beautiful as Highway 1 |url=https://www.cntraveler.com/galleries/2016-05-02/the-us-road-trip-thats-as-beautiful-as-highway-1 |work=[[Condé Nast Traveler]] |url-access=subscription |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729060047/https://www.cntraveler.com/galleries/2016-05-02/the-us-road-trip-thats-as-beautiful-as-highway-1}}</ref> The Oregon Coast Highway then crosses the [[Yaquina Bay Bridge]] into [[Newport, Oregon|Newport]] and serves as the western terminus of [[U.S. Route 20|US&nbsp;20]], a transcontinental route to [[Boston]] and the longest highway in the United States.<ref>{{cite web |last=Weingroff |first=Richard |title=What is the longest road in the United States? |url=https://www.fhwa.dot.gov/infrastructure/longest.cfm |publisher=Federal Highway Administration |accessdate=July 28, 2023 |archive-date=June 19, 2018 |url-status=live |archive-url=https://web.archive.org/web/20180619063537/https://www.fhwa.dot.gov/infrastructure/longest.cfm}}</ref> US&nbsp;101 continues along the coastline and [[Siletz Bay]] into [[Lincoln City, Oregon|Lincoln City]], where it serves as the city's main street for {{convert|7|mi|km}}<ref name="Bulletin">{{cite news |last=Gottberg Anderson |first=John |date=January 5, 2014 |title=Oregon's scenic byways |url=https://www.bendbulletin.com/lifestyle/oregon-s-scenic-byways/article_d7910ad2-d26d-5a60-bfbe-82c924fe63cd.html |work=[[Bend Bulletin]] |accessdate=July 28, 2023 |archive-date=December 2, 2022 |url-status=live |archive-url=https://web.archive.org/web/20221202025648/https://www.bendbulletin.com/lifestyle/oregon-s-scenic-byways/article_d7910ad2-d26d-5a60-bfbe-82c924fe63cd.html}}</ref> and turns away from the coast to bypass the [[Cascade Head]] biosphere reserve.{{sfnp|Gratreak|Stuart|Jones|Becker|2015|p=14}}<ref>{{cite news |last=Roemeling |first=Alisha |date=January 18, 2014 |title=Cascade Head hike ends with great views |url=https://www.statesmanjournal.com/story/news/2014/01/19/cascade-head-hike-ends-with-great-views/4608247/ |work=Statesman Journal |accessdate=July 28, 2023 |archive-date=March 16, 2024 |url-status=live |archive-url=https://web.archive.org/web/20240316074054/https://www.statesmanjournal.com/story/news/2014/01/19/cascade-head-hike-ends-with-great-views/4608247/}}</ref> The highway briefly returns to the coastline before beginning a long inland stretch that follows the [[Nestucca River]] and other streams to [[Tillamook, Oregon|Tillamook]].<ref name="google"/>{{sfnp|Gratreak|Stuart|Jones|Becker|2015|pp=9–11}}

US&nbsp;101 passes the [[Tillamook County Creamery Association]] factory and travels northwest along [[Tillamook Bay]] to rejoin the coast near [[Garibaldi, Oregon|Garibaldi]], but later turns inland to skirt [[Nehalem Bay]] and avoid [[Cape Falcon, Oregon|Cape Falcon]].{{sfnp|Gratreak|Stuart|Jones|Becker|2015|pp=9–11}} The highway travels around the community of [[Cannon Beach, Oregon|Cannon Beach]], home to the landmark [[Haystack Rock]],<ref name="CNTraveler"/><ref>{{cite news |last=Hale |first=Jamie |date=July 11, 2017 |title=The 12 most iconic landmarks on the Oregon coast |url=https://www.oregonlive.com/travel/2017/07/the_12_most_iconic_landmarks_o.html |work=The Oregonian |accessdate=July 28, 2023 |archive-date=August 10, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230810195756/https://www.oregonlive.com/travel/2017/07/the_12_most_iconic_landmarks_o.html}}</ref> and turns northeast to bypass [[Tillamook Head]] and intersect [[U.S. Route 26|US&nbsp;26]]—a major route to [[Portland, Oregon|Portland]].<ref name="OR-Map"/> US&nbsp;101 continues north along the [[Necanicum River]] to reach the coast at [[Seaside, Oregon|Seaside]] and travel through the city and nearby beach communities. The highway turns northeast and crosses [[Youngs Bay]] from [[Warrenton, Oregon|Warrenton]] to [[Astoria, Oregon|Astoria]], where it meets the western terminus of [[U.S. Route 30|US&nbsp;30]]; that highway continues into downtown Astoria and east towards [[Portland, Oregon|Portland]].<ref name="google"/><ref name="OR-Map"/> US&nbsp;101 turns south onto a loop ramp that leads north to the [[Astoria–Megler Bridge]], a {{convert|4|mi|km|adj=mid|-long}} bridge that spans the mouth of the [[Columbia River]] and carries the highway into Washington.<ref name="OR-Map"/><ref name="Oregonian-AstoriaBridge">{{cite news |last=Read |first=Richard |date=December 27, 2015 |title=Astoria-Megler Bridge straddles 4 miles, guides ship pilots, withstands gusts: 'Spanning Oregon' |url=https://www.oregonlive.com/pacific-northwest-news/2015/12/astoria-megler_bridge_columbia.html |work=The Oregonian |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729063237/https://www.oregonlive.com/pacific-northwest-news/2015/12/astoria-megler_bridge_columbia.html}}</ref>

===Washington===
{{Main|U.S. Route 101 in Washington}}
[[File:US 101 northbound approaching downtown Aberdeen, WA.jpg|thumb|right|Northbound view of US&nbsp;101 as it descends into downtown [[Aberdeen, Washington]], to intersect [[U.S. Route 12|US&nbsp;12]]|alt=Looking down from a one-way bridge with two lanes at a city skyline with low-slung buildings and hills in the background; a sign reading "101 North Hoquiam, Port Angeles; 12 East Olympia" hangs over the highway.]]

US&nbsp;101 enters Washington state at the north end of the Astoria–Megler Bridge and immediately turns west to follow the Columbia River. The highway traverses [[Fort Columbia State Park]] in a tunnel and passes through [[Chinook, Washington|Chinook]] on the north side of the river's mouth towards [[Ilwaco, Washington|Ilwaco]], near [[Cape Disappointment (Washington)|Cape Disappointment]].<ref>{{cite news |last=Zahn |first=Andy |date=June 14, 2012 |title=Explore century-old Fort Columbia, now a state park |url=https://tdn.com/lifestyles/explore-century-old-fort-columbia-now-a-state-park/article_0223fa04-b700-11e1-8125-0019bb2963f4.html |work=[[The Daily News (Longview, Washington)|The Daily News]] |accessdate=July 29, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729070332/https://tdn.com/lifestyles/explore-century-old-fort-columbia-now-a-state-park/article_0223fa04-b700-11e1-8125-0019bb2963f4.html}}</ref> From Ilwaco, US&nbsp;101 briefly travels north before turning east at [[Seaview, Washington|Seaview]], the southernmost city on the [[Long Beach Peninsula]],<ref>{{cite news |last=Frank |first=Michael |date=May 5, 1991 |title=Historic cape in the Pacific Northwest |at=sec. 5, p. 8 |url=https://www.nytimes.com/1991/05/05/travel/historic-cape-in-the-pacific-northwest.html |work=The New York Times |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730052319/https://www.nytimes.com/1991/05/05/travel/historic-cape-in-the-pacific-northwest.html}}</ref> and following [[Willapa Bay]] to a junction with [[Washington State Route 4|State Route 4]] (SR&nbsp;4) on the [[Naselle River]].<ref>{{cite web |date=April 2, 2018 |title=Corridor Sketch Summary – US 101/SR 100: Astoria Bridge to Cosmopolis |url=https://wsdot.wa.gov/sites/default/files/2021-10/CSS210-US101SR100-AstoriaBridge-Cosmopolis.pdf |publisher=Washington State Department of Transportation |accessdate=July 29, 2023 |archive-date=December 8, 2023 |url-status=live |archive-url=https://web.archive.org/web/20231208204724/https://wsdot.wa.gov/sites/default/files/2021-10/CSS210-US101SR100-AstoriaBridge-Cosmopolis.pdf}}</ref> The highway continues along the east side of the bay through [[South Bend, Washington|South Bend]] to [[Raymond, Washington|Raymond]], where it travels inland to cross the forested [[Willapa Hills]] to reach [[Aberdeen, Washington|Aberdeen]]. US&nbsp;101 enters the city by crossing the [[Chehalis River (Washington)|Chehalis River]] and turns west onto a pair of one-way streets after an intersection with [[U.S. Route 12|US&nbsp;12]].<ref name="google"/><ref name="WSDOT-Map">{{cite WSDOT map |year=2014 |accessdate=July 29, 2023}}</ref>

The streets travel through western Aberdeen and neighboring [[Hoquiam, Washington|Hoquiam]], where the highway is split by the [[Hoquiam River]], and rejoin north of downtown. The highway continues north along inland streams into the [[Quinault Indian Reservation]], which it enters near [[Lake Quinault]] at the edge of [[Olympic National Park]].<ref name="OlympicNP-Map">{{cite map |date=July 2021 |title=Olympic National Park |url=https://www.nps.gov/olym/planyourvisit/upload/olymmap1.pdf |publisher=[[National Park Service]] |accessdate=July 29, 2023 |archive-date=September 24, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230924213125/https://www.nps.gov/olym/planyourvisit/upload/OLYMmap1.pdf}}</ref> US&nbsp;101 circumnavigates the [[Olympic Peninsula]] and provides the main access to the national park and various sites via spur roads;<ref name="NatGeo">{{cite news |last=Nelson |first=Andrew |date=September 14, 2010 |title=Road Trip: The Olympic Peninsula, Washington |url=https://www.nationalgeographic.com/travel/article/olympic-peninsula-washington-road-trip |archive-url=https://web.archive.org/web/20210420011715/https://www.nationalgeographic.com/travel/article/olympic-peninsula-washington-road-trip |url-status=dead |archive-date=April 20, 2021 |work=[[National Geographic]] |accessdate=July 29, 2023}}</ref> there are no roads that cross the [[Olympic Mountains]], which separate areas of the national park and adjacent [[Olympic National Forest]].<ref name="OlympicNP-Map"/><ref name="HAER-OlympicNP">{{cite web |last=Swope |first=Caroline |editor-last=Ottoboni |editor-first=Gina |date=March 2004 |title=HAER No. WA-166: Olympic National Park Road System |pages=6, 9, 21–22 |url=http://npshistory.com/publications/olym/haer-wa-166.pdf |work=[[Historic American Engineering Record]] |publisher=National Park Service |accessdate=August 6, 2023 |archive-date=August 6, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230806235712/http://npshistory.com/publications/olym/haer-wa-166.pdf}}</ref> The highway turns west from Lake Quinault to reach the Pacific coastline, which it follows for {{convert|15|mi|km}} between [[Queets, Washington|Queets]] and [[Ruby Beach]] within Olympic National Park.<ref>{{cite news |last=Duncan |first=Don |date=December 19, 1993 |title=Sand for all seasons: Where sea meets land in wild abandon, the state's long, dramatic coastline presents a pageant of history and nature |page=L1 |url=https://archive.seattletimes.com/archive/?date=19931219&slug=1737717 |work=The Seattle Times |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730052320/https://archive.seattletimes.com/archive/?date=19931219&slug=1737717}}</ref> US&nbsp;101 then heads northeast to follow the [[Hoh River]] upstream and intersects the main access road to the [[Hoh Rainforest]].<ref name="Bee-1952">{{cite news |date=June 25, 1952 |title=Olympic Loop Highway in Washington is scenic marvel |page=V18 |work=[[The Sacramento Bee]] |url=https://www.newspapers.com/article/the-sacramento-bee-olympic-loop-highway/129121073/ |via=[[Newspapers.com]] |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730070123/https://www.newspapers.com/article/the-sacramento-bee-olympic-loop-highway/129121073/}}</ref> It then travels north through [[Forks, Washington|Forks]] and follows the [[Sol Duc River]] east to re-enter the national park.<ref name="google"/><ref name="OlympicNP-Map"/>

[[File:U.S. Route 101 flight over Elwha.webm|thumb|right|Aerial view of US&nbsp;101 near the [[Elwha River]] west of [[Port Angeles, Washington]]|alt=Video of a drone flight over a highway as it crosses a river in a dense coniferous forest.]]

US&nbsp;101 travels along the southern shore of [[Lake Crescent]], one of the deepest lakes in the state,<ref>{{cite news |last=Judd |first=Ron |date=August 8, 2014 |title=Our deep lakes incite curiosity and conjure legends |url=https://www.seattletimes.com/life/lifestyle/our-deep-lakes-incite-curiosity-and-conjure-legends/ |work=The Seattle Times |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730052319/https://www.seattletimes.com/life/lifestyle/our-deep-lakes-incite-curiosity-and-conjure-legends/}}</ref> and the foothills of the Olympic Mountains until it crosses the [[Elwha River]] near the site of the demolished [[Elwha Dam]].<ref>{{cite news |date=October 20, 2016 |title=Elwha River bridge could need replacement after dam removal |url=https://www.spokesman.com/stories/2016/oct/20/elwha-river-bridge-could-need-replacement-after-da/ |work=[[The Spokesman-Review]] |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730052319/https://www.spokesman.com/stories/2016/oct/20/elwha-river-bridge-could-need-replacement-after-da/}}</ref> The highway enters [[Port Angeles, Washington|Port Angeles]] and uses city streets to reach the northernmost point of US&nbsp;101,<ref name="NatGeo"/><ref name="Bee-1952"/> near the [[ferry terminal]] for the [[Puget Sound Navigation Company|Black Ball Line]] to [[Victoria, British Columbia]].<ref name="WSDOT-Map"/> The four-lane highway turns east to follow the [[Strait of Juan de Fuca]] through a rural prairie and becomes a [[super two|super two expressway]] as it bypasses [[Sequim, Washington|Sequim]].<ref>{{cite web |date=March 28, 2018 |title=Corridor Sketch Summary – US 101/SR 104/SR 117: US 101 Jct at SR 112 to SR 104 Jct at SR 3 |url=https://wsdot.wa.gov/sites/default/files/2021-10/CSS213-US101SR104SR117-US101JctatSR112-SR104JctatSR3.pdf |publisher=Washington State Department of Transportation |accessdate=July 29, 2023 |archive-date=March 11, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230311211330/https://wsdot.wa.gov/sites/default/files/2021-10/CSS213-US101SR104SR117-US101JctatSR112-SR104JctatSR3.pdf}}</ref> US&nbsp;101 dips south to travel around [[Sequim Bay]] and turns south to follow [[Discovery Bay, Washington|Discovery Bay]] to a junction with [[Washington State Route 20|SR&nbsp;20]], which serves [[Port Townsend, Washington|Port Townsend]] and the [[North Cascades]].<ref name="WSDOT-Map"/>

The highway travels south and crosses a [[mountain pass|pass]] in the Olympic Mountains near [[Mount Walker (Washington)|Mount Walker]] before it reaches the west shore of [[Hood Canal]], which it follows for more than {{convert|50|mi|km}}.<ref name="Bee-1952"/><ref>{{cite news |last=Blair Jr. |first=Seabury |date=February 7, 1993 |title=Hike o' the Month: They didn't name Mt. Walker that for nothing |page=3 |work=[[Kitsap Sun]] |department=R&R |url=https://www.newspapers.com/article/kitsap-sun-hike-o-the-month-they-didn/129121162/ |via=Newspapers.com |accessdate=July 29, 2023 |archive-date=July 30, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230730070125/https://www.newspapers.com/article/kitsap-sun-hike-o-the-month-they-didn/129121162/}}</ref> US&nbsp;101 passes several [[List of Washington state parks|state parks]] and additional access points for the national park, including [[Lake Cushman]] near [[Hoodsport, Washington|Hoodsport]].<ref name="OlympicNP-Map"/> It leaves Hood Canal on the [[Skokomish Indian Reservation]] and continues south on a super two bypass around [[Shelton, Washington|Shelton]], where it intersects [[Washington State Route 3|SR&nbsp;3]]. US&nbsp;101 then becomes a freeway and cuts across several inlets and bays of [[Puget Sound]] as it turns southeast towards the Olympia area.<ref>{{cite web |date=January 27, 2019 |title=Corridor Sketch Summary – US 101: SR 102 Jct (Shelton) to I-5 Jct (Tumwater/Olympia) |url=https://wsdot.wa.gov/sites/default/files/2021-10/CSS215-US101-SR102JctShelton-i5JctTumwaterOlympia.pdf |publisher=Washington State Department of Transportation |accessdate=July 29, 2023 |archive-date=March 6, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230306175032/https://wsdot.wa.gov/sites/default/files/2021-10/CSS215-US101-SR102JctShelton-i5JctTumwaterOlympia.pdf}}</ref> The freeway merges with [[Washington State Route 8|SR&nbsp;8]] and continues southeast to reach its northern terminus at I-5 in [[Tumwater, Washington|Tumwater]],<ref name="Mercury"/> near the [[Washington State Capitol]] campus in nearby Olympia.<ref name="google"/><ref name="WSDOT-Map"/>

The section between Lake Crescent and Sequim is generally [[Direction, position, or indication sign|signed]] east–west,<ref name="WSDOT-log"/> while the section south of the intersection with SR&nbsp;20 is signed north–south but turned 180 degrees.<ref name="Mercury"/> The direct route between Aberdeen and Olympia uses US&nbsp;12 and SR&nbsp;8, which complete the Olympic Loop Highway.<ref name="WSDOT-Map"/>

==Numbering==

According to the [[American Association of State Highway and Transportation Officials]]'s (AASHTO) numbering scheme for [[United States Numbered Highways]], three-digit route numbers are generally subsidiaries of two-digit primary routes. Of these two-digit routes, the principal north–south routes were assigned numbers ending in 1.<ref name="Davis">{{cite news |last=Davis |first=Emily C. |date=August 7, 1927 |title=An American sign language is called greatest traffic need |page=D1 |work=[[Knoxville News Sentinel]] |agency=[[Society for Science|Science Service]] |url=https://www.newspapers.com/article/the-knoxville-news-sentinel-an-american/128919239/ |via=Newspapers.com |accessdate=July 26, 2023 |archive-date=July 26, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230726214352/https://www.newspapers.com/article/the-knoxville-news-sentinel-an-american/128919239/}}</ref><ref>{{cite news |last=Watson |first=Elmo Scott |date=April 16, 1927 |title=U.S. System of Highways |page=5 |work=[[St. Charles Herald]] |location=Hahnville, Louisiana |url=https://www.newspapers.com/article/the-st-charles-herald-us-system-of-hi/128918987/ |via=Newspapers.com |accessdate=July 26, 2023 |archive-date=July 26, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230726214350/https://www.newspapers.com/article/the-st-charles-herald-us-system-of-hi/128918987/}}</ref> US&nbsp;101 is an exception to the three-digit rule due to its role as the westernmost major route;<ref name="LATimes-Numbers">{{cite news |last=Fausset |first=Richard |date=November 13, 2001 |title=Highway numerology muddled by potholes in logic |page=B2 |url=https://www.latimes.com/archives/la-xpm-2001-nov-13-me-3653-story.html |work=Los Angeles Times |accessdate=July 27, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728044816/https://www.latimes.com/archives/la-xpm-2001-nov-13-me-3653-story.html}}</ref> it is treated as a primary, two-digit route with a "first digit" of 10, rather than a spur of [[U.S. Route 1|US&nbsp;1]], which is located along the east coast.<ref name="Davis"/><ref>{{cite news |last=Mall |first=Scott |date=February 23, 2021 |title=FreightWaves Classics: National Highway System helps commerce move from coast-to-coast |url=https://www.freightwaves.com/news/freightwaves-classics%3A-national-highway-system-helps-commerce-move-from-coast-to-coast |work=FreightWaves |url-status=dead |archive-url=https://web.archive.org/web/20210223193556/https://www.freightwaves.com/news/freightwaves-classics%3A-national-highway-system-helps-commerce-move-from-coast-to-coast |archive-date=February 23, 2021 |accessdate=June 27, 2023}}</ref>

==History==

===Establishment and early development===
[[File:101 Solana Beach.jpg|thumb|right|upright=0.75|Historic Route 101 in Solana Beach, California|alt=View from a sidewalk of several banners and signs with the U.S. 101 shield displayed in decorative fashion alongside an American flag pattern.]]

US&nbsp;101 was established as part of the initial United States Numbered Highway System that was developed by the [[American Association of State Highway Officials]] (AASHO) in the 1920s. The preliminary plan recommended in 1925 had the highway terminate at [[San Diego]] in the south and in [[Port Angeles, Washington]], to the north.<ref>{{cite report |author=Joint Board on Interstate Highways |date=October 30, 1925 |title=Report of Joint Board on Interstate Highways |page=57 |publisher=[[United States Department of Agriculture]] |oclc=71026428 |url=https://en.wikisource.org/wiki/Report_of_Joint_Board_on_Interstate_Highways_October_30,_1925 |via=[[Wikisource]] |accessdate=July 26, 2023 |archive-date=November 14, 2017 |url-status=live |archive-url=https://web.archive.org/web/20171114145350/https://en.wikisource.org/wiki/Report_of_Joint_Board_on_Interstate_Highways_October_30,_1925}}</ref><ref>{{cite news |date=December 23, 1925 |title=Two highways of California have military value |page=19 |work=The Sacramento Bee |url=https://www.newspapers.com/article/the-sacramento-bee-two-highways-of-calif/128919157/ |via=Newspapers.com |accessdate=July 26, 2023 |archive-date=July 27, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230727041456/https://www.newspapers.com/article/the-sacramento-bee-two-highways-of-calif/128919157/}}</ref> The final plan extended US&nbsp;101 within Washington around the east side of the Olympic Peninsula to Olympia<ref>{{cite news |date=January 1928 |title=United States Numbered Highways |page=34 |work=[[California Highways and Public Works]] |publisher=[[California Department of Public Works]] |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/11001 |via=California Department of Transportation Library Digital Collections |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729021142/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/11001}}</ref> and was adopted by the AASHO on November 11, 1926.<ref name="USH"/><ref>{{cite web |last=Weingroff |first=Richard F. |year=1997 |title=From names to numbers: the origins of the U.S. Numbered Highway System |url=https://highways.dot.gov/highway-history/general-highway-history/names-numbers-origins-us-numbered-highway-system |work=General Highway History |publisher=Federal Highway Administration |accessdate=July 26, 2023 |archive-date=July 27, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230727041533/https://highways.dot.gov/highway-history/general-highway-history/names-numbers-origins-us-numbered-highway-system}}</ref> The first section of US&nbsp;101 to be signed in California was between San Diego and Los Angeles in January 1928, which was followed by the rest of the route later in the year.<ref>{{cite news |last=O'Brien |first=M. A. |date=May 1952 |title=History of United States Numbered Highways |pages=54–55 |volume=31 |issue=5–6 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://libraryarchives.metro.net/dpgtl/Californiahighways/chpw_1952_mayjun.pdf |via=[[Los Angeles County Metropolitan Transportation Authority|Metro]] Transportation Research Library & Archive |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802005147/https://libraryarchives.metro.net/dpgtl/Californiahighways/chpw_1952_mayjun.pdf}}</ref>

Portions of the coastal highway had already been constructed by the respective state governments and also followed foot and wagon routes developed in earlier centuries.<ref name="SDUT-2017">{{cite news |last=Garrick |first=David |date=August 20, 2017 |title=Original Highway 101, precursor to I-5, was first official north-south San Diego route |page=1 |url=https://www.sandiegouniontribune.com/news/politics/sd-me-101-history-20170818-story.html |work=[[The San Diego Union-Tribune]] |accessdate=July 26, 2023 |archive-date=July 27, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230727040025/https://www.sandiegouniontribune.com/news/politics/sd-me-101-history-20170818-story.html}}</ref> Among these was [[El Camino Real (California)|El Camino Real]] in California, which was formed by the [[Portolá expedition]] in 1769 and 1770 and connected the historic [[Spanish missions in California|Spanish missions]], pueblos, and [[presidio]]s.<ref>{{cite news |last=Lieu |first=Alex |date=August 6, 1995 |title=Ventura Freeway: Valley lifeline follows path taken by explorers |page=B3 |work=Los Angeles Times |url=https://www.newspapers.com/article/the-los-angeles-times-ventura-freeway-v/129058919/ |via=Newspapers.com |accessdate=July 28, 2023 |archive-date=July 29, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230729040039/https://www.newspapers.com/article/the-los-angeles-times-ventura-freeway-v/129058919/}}</ref><ref>{{cite web |title=The California Missions Trail |url=https://www.parks.ca.gov/?page_id=22722 |publisher=[[California State Parks]] |accessdate=July 28, 2023 |archive-date=July 26, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230726200321/http://www.parks.ca.gov/?page_id=22722}}</ref> The California state government chose a section of El Camino Real in San Bruno in 1912 to become the first paved highway in the state.<ref>{{cite news |date=August 8, 1912 |title=State's $18,000,000 highway is started |page=5 |work=[[San Francisco Examiner]] |url=https://www.newspapers.com/article/the-san-francisco-examiner-states-180/129284283/ |via=Newspapers.com |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802011235/https://www.newspapers.com/article/the-san-francisco-examiner-states-180/129284283/}}</ref><ref>{{cite news |last=Clifford |first=Jim |date=November 6, 2017 |title=State highway system started in San Bruno |url=https://www.smdailyjournal.com/news/local/state-highway-system-started-in-san-bruno/article_22623e8c-c278-11e7-9cd4-83f2563fcd30.html |work=[[San Mateo Daily Journal]] |url-access=subscription |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802011237/https://www.smdailyjournal.com/news/local/state-highway-system-started-in-san-bruno/article_22623e8c-c278-11e7-9cd4-83f2563fcd30.html}}</ref> The San Diego–San Francisco section of El Camino Real was incorporated into the multi-state [[Pacific Highway (U.S.)|Pacific Highway]] in the 1910s;<ref>{{cite map |last=Westgard |first=A. L. |date=September 1915 |title=Map of the Pacific Highway |scale=1:5,000,000 |publisher=[[National Highways Association]] |url=https://www.loc.gov/item/2021668510/ |via=[[Library of Congress]] |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802011237/https://www.loc.gov/item/2021668510/}}</ref><ref>{{cite map |year=1917 |title=Automobile Highway Map of California and Western Nevada |scale=1:1,450,000 |publisher=[[California State Automobile Association]] |location=San Francisco |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~289517~90061476 |via=David Rumsey Map Collection |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802011235/https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~289517~90061476}}</ref> other sections of US&nbsp;101 in California used the existing Redwood Highway, which was constructed from 1917 to 1923,<ref name="Redwood">{{cite book |last=Bearss |first=Edwin C. |date=September 1, 1969 |title=Redwood National Park: History, Basic Data |chapter=Chapter IX. Trails, Roads, Ferries, and Freighters |pages=146–147 |publisher=National Park Service |location=Washington, D.C. |oclc=8364201 |chapter-url=https://www.nps.gov/parkhistory/online_books/redw/history9b.htm |accessdate=August 1, 2023 |archive-date=October 28, 2021 |url-status=live |archive-url=https://web.archive.org/web/20211028172009/https://www.nps.gov/parkhistory/online_books/redw/history9b.htm}}</ref> and Coast Highway.<ref>{{cite news |date=January 1926 |title=Commission approves California routes in system of United States Highways |page=13 |volume=3 |issue=1 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://libraryarchives.metro.net/dpgtl/Californiahighways/ch_1926_jan.pdf |via=Metro Transportation Research Library & Archive |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802011237/https://libraryarchives.metro.net/dpgtl/Californiahighways/ch_1926_jan.pdf}}</ref>

[[File:HUMBUG MOUNTAIN - NARA - 520143.jpg|thumb|right|A section of the Oregon Coast Highway near [[Humbug Mountain]], photographed in 1938|alt=Black-and-white photograph of a narrow road winding around the cliffs overlooking the ocean.]]

Construction of the Oregon Coast Highway began in 1921, two years after a state [[referendum]] that voted in favor of funding the development of highways with a one-cent [[gas tax]]. At the time, several short wagon roads and plank roads connected settlements on the coast, and overland travel primarily used beaches.{{sfnp|Gratreak|Stuart|Jones|Becker|2015|p=39}}<ref name="Husing">{{cite magazine |last=Husing |first=Onno |date=March 2008 |title=A History of U.S. Highway 101 |pages=3–4 |magazine=Oregon Coastal Notes |publisher=[[Oregon Coastal Zone Management Association]] |url=http://www.oczma.org/pdfs/U.S.Highway%20101%20Final.pdf |url-status=dead |archive-url=https://web.archive.org/web/20150916191128/http://www.oczma.org/pdfs/U.S.Highway%20101%20Final.pdf |archive-date=September 16, 2015 |accessdate=July 26, 2023}}</ref> The highway was gradually constructed and paved in the 1920s, but a set of six [[ferry]] crossings remained. These ferries were operated by private companies until the state government acquired them in 1927 with plans to replace them with bridges.{{sfnp|Husing|2008|p=11}} The five major Oregon bridges on US&nbsp;101 were designed by state engineer [[Conde B. McCullough]] and opened by 1936 using funding from the federal government's [[New Deal]] programs. As automobile traffic on the Oregon Coast increased, other sections were realigned to avoid rugged terrain or bypassed with tunnels.<ref>{{cite encyclopedia |last=Hadlow |first=Robert W. |date=August 11, 2022 |title=US 101 (Oregon Coast Highway) |url=https://www.oregonencyclopedia.org/articles/highway_101_oregon_coast_highway_/ |encyclopedia=[[Oregon Encyclopedia]] |accessdate=July 26, 2023 |archive-date=May 18, 2021 |url-status=live |archive-url=https://web.archive.org/web/20210518150359/https://www.oregonencyclopedia.org/articles/highway_101_oregon_coast_highway_/}}</ref> The Oregon Coast Highway was declared complete on October 3, 1936, and cost $25&nbsp;million to construct (equivalent to ${{Format price|{{Inflation|US-GDP|25000000|1936}}}} in {{Inflation-year|US-GDP}} dollars).{{sfnp|Husing|2008|pp=14–15}}{{inflation-fn|US-GDP}}

Washington completed the final sections of the Olympic Loop Highway between 1927 and 1931 for $11&nbsp;million (equivalent to ${{Format price|{{Inflation|US-GDP|11000000|1931}}}} in {{Inflation-year|US-GDP}} dollars).{{inflation-fn|US-GDP}}<ref>{{cite news |date=August 24, 1931 |title=Olympic Loop Highway completed; Big celebration Wednesday will signal opening |page=12 |work=The Seattle Times}}</ref> The project paved several existing sections of the state roads and also constructed {{convert|7|mi|km}} of new highway from the [[Queets River]] to Ruby Beach near [[Kalaloch, Washington|Kalaloch]]. Portions of US&nbsp;101 passed through lands that were later incorporated into Olympic National Park when it was established in 1938; under the [[National Park Service]], sections of the Crescent Lake Highway were widened and improved in 1949.<ref>{{cite web |title=Historic Highway US 101 |url=https://wsdot.wa.gov/construction-planning/protecting-environment/historic-highways/historic-highway-us-101 |publisher=Washington State Department of Transportation |accessdate=July 26, 2023 |archive-date=August 17, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230817210516/https://wsdot.wa.gov/construction-planning/protecting-environment/historic-highways/historic-highway-us-101}}</ref> The [[Washington State Highway Commission]] submitted an application to AASHO in 1955 to extend US&nbsp;101 northeast from Discovery Bay to [[Whidbey Island]] and [[Mount Vernon, Washington|Mount Vernon]], where it would terminate at [[U.S. Route 99|US&nbsp;99]].<ref>{{cite news |date=September 20, 1955 |title=Direct link between Camano, Whidbey islands is proposed |page=20 |work=The Everett Herald |url=https://www.newspapers.com/article/the-daily-herald-direct-link-between-cam/140326877/ |via=Newspapers.com |accessdate=March 14, 2024 |archive-date=March 14, 2024 |url-status=live |archive-url=https://web.archive.org/web/20240314203144/https://www.newspapers.com/article/the-daily-herald-direct-link-between-cam/140326877/}}</ref> The proposal was rejected by AASHO for being too long of a detour and including a tolled ferry crossing.<ref>{{cite web |date=July 21, 1955 |title=An Application from the State Highway Department of Washington for the extension of U.S. Route No. 101 |pages=2–3, 8 |publisher=[[Washington State Highway Commission]], American Association of State Highway Officials |url=https://grmservices.grmims.com/vsearch/portal/public/na4/aashto/default |via=AASHTO Route Numbering Archive |accessdate=August 1, 2023 |archive-date=October 2, 2020 |url-status=live |archive-url=https://web.archive.org/web/20201002030140/https://grmservices.grmims.com/vsearch/portal/public/na4/aashto/default}}</ref>

===New alignments and freeways===
[[File:Hyde Street Pier - San Francisco (5765732935).jpg|thumb|right|[[Hyde Street Pier]] in San Francisco, part of the pre-[[Golden Gate Bridge]] alignment of US&nbsp;101|alt=An overhead structure labeled "Hyde St. Pier" frames a historic ferryboat alongside a US 101 shield and older sailing ship.]]

US&nbsp;101 was split into two routes in the San Francisco Bay Area between San Jose and San Francisco in 1929:<ref>{{AASHTO minutes |year=1928A |page=9 |accessdate=August 2, 2023}}</ref> US&nbsp;101W followed El Camino Real on the San Francisco Peninsula for {{convert|50|mi|km}}; US&nbsp;101E traversed the [[East Bay]] for {{convert|54|mi|km}} to [[Oakland, California|Oakland]], where it turned west on a [[Ferries of San Francisco Bay|cross-bay ferry]] to San Francisco.<ref>{{cite news |date=November 1934 |title=Court to clarify Sign Act provision |page=26 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/6495 |via=California Department of Transportation Library Digital Collections |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802073841/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/6495}}</ref><ref>{{cite map |year=1930 |title=Road Map of the State of California |scale=1:1,463,040 |at=[https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239601~5511906 San Francisco Bay Region] inset |publisher=California Department of Public Works |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239599~5511899 |via=David Rumsey Map Collection |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802073840/https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239599~5511899}}</ref> The branches converged in Downtown San Francisco and traveled along city streets to the [[Hyde Street Pier]], where the highway continued on automobile ferries to [[Sausalito, California|Sausalito]] at the south end of the Redwood Highway.<ref>{{cite news |date=March 26, 1930 |title=Redwood Highway terminal routing plan decided on |page=24 |work=The Sacramento Bee |url=https://www.newspapers.com/article/the-sacramento-bee-redwood-highway-termi/129297913/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802081103/https://www.newspapers.com/article/the-sacramento-bee-redwood-highway-termi/129297913/}}</ref> By 1936, US&nbsp;101E had been eliminated in favor of the route on the west side, which was re-designated as US&nbsp;101.<ref>{{cite map |year=1936 |title=Road Map of the State of California, 1936–1937 |scale=1:1,463,040 |at=[https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239593~5511895 San Francisco Bay Region] inset |publisher=California Department of Public Works |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239591~5511894 |via=David Rumsey Map Collection |accessdate=August 2, 2023 |archive-date=August 10, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230810193743/https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239591~5511894}}</ref>

The Hyde Street–Sausalito ferry was removed from US&nbsp;101 following the May 1937 completion of the [[Golden Gate Bridge]], which would carry the highway from San Francisco to Marin County.<ref>{{cite news |last=Viall |first=Tim |date=October 29, 2014 |title=Pier into San Francisco's past |url=https://www.recordnet.com/story/lifestyle/travel/2014/10/30/pier-into-san-francisco-s/36040619007/ |work=[[The Record (Stockton, California)|The Record]] |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802073841/https://www.recordnet.com/story/lifestyle/travel/2014/10/30/pier-into-san-francisco-s/36040619007/}}</ref><ref>{{cite news |date=June 12, 1937 |title=These rules to govern travel across bridge |page=7 |work=[[The Press Democrat]] |url=https://www.newspapers.com/article/the-press-democrat-these-rules-to-govern/129298114/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802073840/https://www.newspapers.com/article/the-press-democrat-these-rules-to-govern/129298114/}}</ref> It was the [[List of longest suspension bridge spans|longest suspension bridge]] in the world at the time of its construction and was funded by a $35&nbsp;million regional [[municipal bond|bond]] (equivalent to ${{Format price|{{Inflation|US-GDP|35000000|1937}}}} in {{Inflation-year|US-GDP}} dollars){{inflation-fn|US-GDP}} that was paid off in 1971.<ref>{{cite news |last=King |first=John |date=May 13, 2012 |title=Golden Gate Bridge construction—and indignation |page=A1 |url=https://www.sfgate.com/bayarea/place/article/Golden-Gate-Bridge-construction-and-indignation-3554707.php |work=San Francisco Chronicle |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802073840/https://www.sfgate.com/bayarea/place/article/Golden-Gate-Bridge-construction-and-indignation-3554707.php}}</ref><ref>{{cite news |date=July 4, 1971 |title=The Golden Gate Bridge is paid for in 34 years |page=S19 |url=https://www.nytimes.com/1971/07/04/archives/the-golden-gate-bridge-is-paid-for-in-34-years.html |work=The New York Times |agency=[[United Press International]] |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802073840/https://www.nytimes.com/1971/07/04/archives/the-golden-gate-bridge-is-paid-for-in-34-years.html}}</ref> The San Jose–San Francisco section of US&nbsp;101 was initially moved from El Camino Real to the [[Bayshore Highway]],<ref>{{cite news |date=December 21, 1937 |title=Fight resumed to regain rating for El Camino Real |page=3 |work=[[Peninsula Times Tribune|Palo Alto Times]] |url=https://www.newspapers.com/article/the-peninsula-times-tribune-fight-resume/129325136/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802204031/https://www.newspapers.com/article/the-peninsula-times-tribune-fight-resume/129325136/}}</ref> a four-lane undivided highway that was constructed between 1924 and 1937 to bypass several towns on the peninsula.<ref>{{cite map |year=1938 |title=Road Map of the State of California, 1938 |scale=1:1,463,040 |at=[https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239590~5511893 S.F. Bay Region] inset |publisher=California Department of Public Works |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239588~5511892 |via=David Rumsey Map Collection |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802204032/https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239588~5511892}}</ref><ref name="CHPW-Bayshore1962">{{cite news |last=Remington |first=W. G. |date=March–April 1962 |title=Bayshore Freeway: San Jose to San Francisco is now all full freeway |pages=5–8 |volume=41 |issue=3–4 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/10501/ |via=California Department of Transportation Library Digital Collections |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802204033/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/10501/}}</ref> El Camino Real was re-designated as US&nbsp;101 Alternate in 1936,<ref>{{cite news |date=August 14, 1936 |title=Alternate sign markers urged for El Camino |page=1 |work=[[San Mateo County Times|San Mateo Times]] |url=https://www.newspapers.com/article/the-times-alternate-sign-markers-urged-f/129326772/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802204035/https://www.newspapers.com/article/the-times-alternate-sign-markers-urged-f/129326772/}}</ref> which sparked outcry from businesses and groups who lobbied for a reversal of the change that was submitted by state officials to AASHO.<ref>{{cite news |date=February 15, 1938 |title=Victory seen in El Camino sign battle |page=1 |work=San Mateo Times |url=https://www.newspapers.com/article/the-times-victory-seen-in-el-camino-sign/129326393/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802210926/https://www.newspapers.com/article/the-times-victory-seen-in-el-camino-sign/129326393/}}</ref><ref>{{cite news |date=February 4, 1938 |title=Board favors Camino for 101 Highway designation |page=1 |work=[[South San Francisco Enterprise Journal|The Enterprise and the South San Francisco Journal]] |url=https://www.newspapers.com/article/the-enterprise-and-the-south-san-francis/129326832/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802210927/https://www.newspapers.com/article/the-enterprise-and-the-south-san-francis/129326832/}}</ref> In 1938, US&nbsp;101 was moved back to El Camino Real and the Bayshore Highway was designated as US&nbsp;101 Bypass.<ref>{{AASHTO minutes |year=1938S |page=12 |accessdate=August 2, 2023}}</ref><ref>{{cite news |date=July 20, 1938 |title=El Camino Real is designated as U.S. Highway No. 101 |page=6A |work=[[The Fresno Bee]] |agency=Associated Press |url=https://www.newspapers.com/article/the-fresno-bee-el-camino-real-is-designa/129299400/ |via=Newspapers.com |accessdate=August 2, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802204033/https://www.newspapers.com/article/the-fresno-bee-el-camino-real-is-designa/129299400/}}</ref>

In the late 1940s, the California state government announced plans to convert most of US&nbsp;101 between Los Angeles and San Francisco to freeways using funds from the [[Collier–Burns Highway Act]] of 1947.<ref>{{cite news |last=McCoy, Jr. |first=George T. |date=January–February 1950 |title=Freeway Unit: New 4-lane divided section is added to Coast Highway |page=29 |volume=29 |issue=1–2 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/2675/ |via=California Department of Transportation Library Digital Collections |accessdate=August 2, 2023 |archive-date=August 3, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230803005755/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/2675/}}</ref><ref>{{cite news |last=Masters |first=Nathan |date=August 15, 2012 |title=L.A.'s first freeways |url=https://www.kcet.org/shows/lost-la/l-a-s-first-freeways |publisher=KCET |accessdate=August 2, 2023 |archive-date=August 3, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230803005754/https://www.kcet.org/shows/lost-la/l-a-s-first-freeways}}</ref> Prior to the act, the Cahuenga Pass Freeway had opened in June 1940 between Hollywood and the San Fernando Valley in Los Angeles to replace a narrow, winding mountain road. It was the city's second freeway and was later extended southeast towards Downtown and renamed the Hollywood Freeway when it was completed on April 16, 1954.<ref name="LATimes-Cahuenga"/> Several other early freeway segments were signed as US&nbsp;101 Bypass or US&nbsp;101 Alternate.<ref>{{cite news |last=Gallagher |first=J. D. |date=September 1950 |title=Chapter XIV: California Highways |pages=106–108 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/1520/ |via=California Department of Transportation Library Digital Collections |accessdate=August 2, 2023 |archive-date=August 3, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230803005754/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/1520/}}</ref> In [[San Luis Obispo, California|San Luis Obispo]], a freeway around the northwest side of downtown was completed by the early 1960s, alongside bypasses of nearby rural towns.<ref>{{cite news |last=Lynem |first=Julie |date=October 12, 2003 |title=How Highway 101 has changed |page=A15 |work=[[The Tribune (San Luis Obispo)|The Tribune]] |location=San Luis Obispo |url=https://www.newspapers.com/article/the-tribune-how-highway-101-has-changed/128941399/ |via=Newspapers.com |accessdate=July 26, 2023 |archive-date=July 27, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230727055545/https://www.newspapers.com/article/the-tribune-how-highway-101-has-changed/128941399/}}</ref> The San Diego–San Francisco section of US&nbsp;101 was designated as El Camino Real by the California state government in 1959 as part of a program to add historic markers on the highway.<ref>{{cite news |date=November 1, 1959 |title=El Camino Real markers, bells to be erected |page=A11 |work=[[Santa Barbara News-Press]] |url=https://www.newspapers.com/article/santa-barbara-news-press-el-camino-real/129407894/ |via=Newspapers.com |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804054741/https://www.newspapers.com/article/santa-barbara-news-press-el-camino-real/129407894/}}</ref>

The [[Santa Ana Freeway]] was planned as a Los Angeles–[[Irvine, California|Irvine]] connector in the late 1930s and constructed in phases, beginning with a section near Downtown Los Angeles that opened in December 1947.<ref>{{cite news |date=December 22, 1947 |title=Santa Ana Parkway sector opens Today |at=sec. 2, p. 2 |work=Los Angeles Times |url=https://www.newspapers.com/article/the-los-angeles-times-santa-ana-parkway/129406181/ |via=Newspapers.com |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804054739/https://www.newspapers.com/article/the-los-angeles-times-santa-ana-parkway/129406181/}}</ref><ref>{{cite news |last=Cortelyou |first=Spencer V. |date=July–August 1948 |title=New freeway: East Los Angeles motorists are saved driving time |pages=1, 15–17 |volume=27 |issue=7–8 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/2397/ |via=California Department of Transportation Library Digital Collections |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804052517/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/2397/}}</ref> US&nbsp;101 was later moved onto sections of the freeway, which was completed in 1958 and served as a continuation of the Hollywood Freeway.<ref>{{cite news |last=Hetherington |first=J. D. |date=July–August 1958 |title=Irvine–El Toro: New Santa Ana Freeway section completed in Orange County |pages=23–24 |volume=37 |issue=7–8 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/13154/ |via=California Department of Transportation Library Digital Collections |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804052537/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/13154/}}</ref><ref>{{cite map |year=1959 |title=Road Map of the State of California, 1959 |scale=1:1,411,705 |at=Los Angeles and Vicinity inset |publisher=California Department of Public Works |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239540~5511860 |via=David Rumsey Map Collection |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804052526/https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239540~5511860}}</ref> By the time it was completed, sections of the freeway between Anaheim and Los Angeles were carrying over 113,000&nbsp;vehicles per day and were planned to be widened to six lanes within a few years.<ref>{{cite news |last=Frischer |first=Don |date=May–June 1956 |title=Tough job: Santa Ana Freeway widening carried out under heavy traffic Conditions |pages=58–59 |volume=35 |issue=5–6 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/8148/ |via=California Department of Transportation Library Digital Collections |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804052536/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/8148/}}</ref><ref>{{cite news |last=Herbert |first=Ray |date=June 22, 1958 |title=Tri-County target: 1200 miles of freeways at cost of four billions |page=26 |work=Los Angeles Times |url=https://www.newspapers.com/article/the-los-angeles-times-freeways-plan-p/129405832/ |via=Newspapers.com |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804060117/https://www.newspapers.com/article/the-los-angeles-times-freeways-plan-p/129405832/}}</ref> The south end of the Santa Ana Freeway merged into the [[San Diego Freeway]], which began construction in 1954 and was completed in 1968.<ref>{{cite news |date=March–April 1957 |title=San Diego Freeway: Governor opens new section |page=32 |volume=36 |issue=3–4 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/5697/ |via=California Department of Transportation Library Digital Collections |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804052534/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/5697/}}</ref><ref>{{cite news |last=Herbert |first=Ray |date=December 9, 1968 |title=San Diego Freeway now reality |at=sec. 2, p. 7 |work=Los Angeles Times |url=https://www.newspapers.com/article/the-los-angeles-times-san-diego-freeway/127342204/ |via=Newspapers.com |accessdate=August 3, 2023 |archive-date=August 10, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230810173406/https://www.newspapers.com/article/the-los-angeles-times-san-diego-freeway/127342204/}}</ref> Both freeways were incorporated into plans for the new [[Interstate Highway System]] in 1955 and assigned to I-5 three years later.<ref>{{cite book |author=Bureau of Public Roads |date=September 1955 |title=General Location of ⁠National System of Interstate Highways |pages=9–10 |publisher=[[United States Government Publishing Office|U.S. Government Printing Office]] |location=Washington, D.C. |oclc=4165975 |url=https://en.wikisource.org/wiki/General_Location_of_National_System_of_Interstate_Highways |via=[[WikiSource]] |accessdate=August 3, 2023 |archive-date=October 9, 2021 |url-status=live |archive-url=https://web.archive.org/web/20211009060116/https://en.wikisource.org/wiki/General_Location_of_National_System_of_Interstate_Highways}}</ref><ref>{{cite letter |last=Johnson |first=A. E. |date=November 10, 1958 |recipient=G. T. McCoy |subject=Route Numbering in California |publisher=American Association of State Highway Officials |url=https://grmservices.grmims.com/vsearch/portal/public/na4/aashto/default |via=AASHTO Route Numbering Archive<!--GRM barcode: 101277386--> |accessdate=August 3, 2023}}</ref>

US&nbsp;101 was truncated to Los Angeles during a 1963 AASHO meeting at the request of the California state government, as I-5 had replaced the stretch to San Diego;<ref name="SDUT-2017"/><ref name="AASHO-1963">{{AASHTO minutes |year=1963S |page=11 |accessdate=August 3, 2023}}</ref> the changes were made ahead of a [[1964 state highway renumbering (California)|major restructuring]] of the state's highway system that took effect on July 1, 1964.<ref>{{cite news |date=March–April 1964 |title=Route renumbering |pages=11–13 |volume=43 |issue=3–4 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/10137/ |via=California Department of Transportation Library Digital Collections |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804052535/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/10137/}}</ref> The old sections of the highway from San Diego to Los Angeles were given local names and later signed as Historic US&nbsp;101 in the late 2010s by local governments.<ref name="SDUT-2017"/> The 1963 action also moved the San Jose–San Francisco section onto the [[Bayshore Freeway]],<ref name="AASHO-1963"/> which was built to replace the Bayshore Highway on US&nbsp;101 Bypass.<ref name="SFC-Bayshore">{{cite news |last=Van Niekerken |first=Bill |date=July 11, 2017 |title=When the Bayshore Freeway was the Bay Area's 'Highway of Tomorrow' |url=https://www.sfchronicle.com/chronicle_vault/article/When-the-Bayshore-Freeway-was-the-Bay-Area-s-11268640.php |work=San Francisco Chronicle |accessdate=August 6, 2023 |archive-date=August 6, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230806225356/https://www.sfchronicle.com/chronicle_vault/article/When-the-Bayshore-Freeway-was-the-Bay-Area-s-11268640.php}}</ref> The freeway had been proposed to address congestion and frequent collisions on the highway, nicknamed "Bloody Bayshore", and opened in stages between 1947 and 1962.<ref name="CHPW-Bayshore1962"/><ref name="SFC-Bayshore"/> The bypassed sections of El Camino Real were renumbered to [[California State Route 82|SR&nbsp;82]] in the Bay Area and signed as business routes of US&nbsp;101 in other cities.<ref>{{cite news |date=May 7, 1964 |title=El Camino isn't 101; now it's Route 82 |page=2 |work=[[Redwood City Tribune]] |url=https://www.newspapers.com/article/redwood-city-tribune-el-camino-isnt-101/129562442/ |via=Newspapers.com |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807010534/https://www.newspapers.com/article/redwood-city-tribune-el-camino-isnt-101/129562442/}}</ref><ref>{{cite map |year=1967 |title=State Highway Map of California, 1967 |scale=1:1,341,120 |at=[https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239518~5511845 San Francisco and Vicinity] inset |publisher=California Department of Public Works |url=https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239516~5511844 |via=David Rumsey Map Collection |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807005032/https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~239516~5511844}}</ref> From the north end of the Bayshore Freeway at [[Interstate 80|I-80]] in San Francisco, US&nbsp;101 was routed west along a section of the [[Central Freeway]], which opened in 1955 and was extended four years later to Van Ness Avenue.<ref>{{cite news |last=Booker |first=B. W. |date=March–April 1958 |title=Report from District IV: Pushed toward completion Bay Area freeway network |pages=4–5 |volume=37 |issue=3–4 |work=California Highways and Public Works |publisher=California Department of Public Works |url=https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/3933/ |via=California Department of Transportation Library Digital Collections |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807005032/https://dot-ca.contentdm.oclc.org/digital/collection/p16436coll4/id/3933/}}</ref><ref>{{cite news |date=April 23, 1959 |title=Central Freeway Open to Traffic |page=3 |work=San Francisco Examiner |url=https://www.newspapers.com/article/the-san-francisco-examiner-central-freew/129566125/ |via=Newspapers.com |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807005032/https://www.newspapers.com/article/the-san-francisco-examiner-central-freew/129566125/}}</ref> Plans to extend the Central Freeway and other thoroughfares through San Francisco to the Golden Gate Bridge were later cancelled by the mid-1960s following [[Highway revolts in the United States|widespread opposition and protests]] from city residents.<ref>{{cite news |last=Chamings |first=Andrew |date=July 26, 2021 |title='A monstrous mistake': Remembering the ugliest thing San Francisco ever built |url=https://www.sfgate.com/local/editorspicks/article/embarcadero-freeway-san-francisco-photos-history-15990662.php |work=SFGate |accessdate=August 6, 2023 |archive-date=August 6, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230806050718/https://www.sfgate.com/local/editorspicks/article/embarcadero-freeway-san-francisco-photos-history-15990662.php}}</ref><ref>{{cite news |last=Lembke |first=Daryl |date=March 20, 1966 |title=S.F. has until Monday to end freeway revolt, get U.S. fund |page=B |work=Los Angeles Times |url=https://www.newspapers.com/article/the-los-angeles-times-sf-has-until-mon/129567450/ |via=Newspapers.com |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807005030/https://www.newspapers.com/article/the-los-angeles-times-sf-has-until-mon/129567450/}}</ref>

[[File:Astoria - Megler Bridge in 2009.jpg|thumb|The [[Astoria–Megler Bridge]], opened in 1966, carries US&nbsp;101 over the [[Columbia River]] north of [[Astoria, Oregon]].|alt=A green-colored truss bridge with two towers crossing a wide river as seen from a distance.]]

Several sections of the Oregon Coast Highway were rebuilt in the 1950s and 1960s to eliminate curves and move the highway further from the coastline in cities such as Cannon Beach.<ref>{{cite news |date=April 5, 1961 |title=Multi-million dollar new coast road cuts driving time |page=6 |work=The Oregonian}}</ref> A {{convert|53|mi|km|adj=mid}} realignment from Brookings to Gold Beach and a more direct route from Bandon to Coos Bay to bypass [[Coquille, Oregon|Coquille]] were completed as part of this program in the early 1960s.<ref>{{cite news |last=Hulen |first=Bob |date=May 10, 1959 |title=Highway work changes face of Oregon's 'forgotten corner' |page=64 |work=The Oregonian}}</ref><ref>{{cite news |date=December 31, 1960 |title=Partially finished Coos-Bandon cutoff open to road traffic |page=3 |work=[[The News-Review]] |url=https://www.newspapers.com/article/the-news-review-partially-finished-coos/129294767/ |via=Newspapers.com |accessdate=August 1, 2023 |archive-date=August 2, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230802045326/https://www.newspapers.com/article/the-news-review-partially-finished-coos/129294767/}}</ref> In 1955, Oregon congressman [[A. Walter Norblad]] unsuccessfully proposed that the US&nbsp;101 corridor be included in the [[Interstate Highway System]] to allow for federal funds to construct a bridge across the Columbia River;<ref>{{cite news |date=April 19, 1955 |title=Coast Highway may become 'national' |page=11 |work=The Seattle Times |agency=Associated Press}}</ref> the proposal was also endorsed by a [[U.S. Army]] official, who also sought a similar designation for the Washington section.<ref>{{cite news |date=April 24, 1955 |title=Army sidesteps bridge proposal |page=7 |work=The Oregonian}}</ref> The Seaside–Astoria section was straightened and realigned onto a [[New Youngs Bay Bridge|new bridge]] over Youngs Bay in 1964.<ref>{{cite news |date=August 31, 1964 |title=It's shorter over Youngs Bay now |page=1 |work=The Oregonian}}</ref> The [[Astoria–Megler Bridge]] over the Columbia River opened to traffic on July 29, 1966, replacing a ferry and comprising the final "link" in US&nbsp;101.<ref name="Oregonian-AstoriaBridge"/><ref>{{cite news |last=Sullivan |first=Ann |date=July 30, 1966 |title=$24 million bridge opens in Astoria; span completes Pacific Coast route |page=1 |work=The Oregonian}}</ref> The northern terminus of US&nbsp;101 was originally at Capitol Way (US&nbsp;99) in downtown Olympia until it was moved to a freeway bypass in December 1958.<ref>{{cite news |last=Batcheldor |first=Matt |date=December 7, 2008 |title=I-5 at 50: It's changed the face of the region |pages=A1–A2 |work=The Olympian |url=https://www.newspapers.com/clip/119394703/i-5-at-50-its-changed-the-face-of-the/ |via=Newspapers.com |accessdate=August 6, 2023 |archive-date=February 24, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230224074503/https://www.newspapers.com/clip/119394703/i-5-at-50-its-changed-the-face-of-the/}}</ref><ref>{{cite news |last=Nelson |first=Stub |date=December 13, 1958 |title=New Olympia freeway opened |pages=1, 4 |work=Seattle Post-Intelligencer}}</ref> The freeway section was extended northwest from Olympia to [[Shelton, Washington|Shelton]] in 1965.<ref>{{cite news |date=July 19, 1965 |title=2-mile freeway section to open |page=21 |work=The Seattle Times}}</ref>

===Modern projects===

The final traffic signal on the {{convert|435|mi|km|adj=mid}} section of US&nbsp;101 between Los Angeles and San Francisco, located at Anacapa Street in Santa Barbara, was removed in November 1991.<ref>{{cite news |last=Feldman |first=Paul |date=November 19, 1991 |title=Lights out on an era |page=A3 |url=https://www.latimes.com/archives/la-xpm-1991-11-19-mn-82-story.html |work=Los Angeles Times |accessdate=August 2, 2023 |archive-date=August 3, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230803060043/https://www.latimes.com/archives/la-xpm-1991-11-19-mn-82-story.html}}</ref> The removal was spurred by the construction of a freeway through Santa Barbara, which was completed the following year and bypassed four signalized intersections.<ref>{{cite news |last=Cannon |first=Lou |date=November 24, 1991 |title=Pulling out all the stops on U.S. 101 |page=A22 |url=https://www.washingtonpost.com/archive/politics/1991/11/24/letter-from-california/a5cde413-d999-454d-b0dd-1745a5575d32/ |newspaper=The Washington Post |accessdate=August 2, 2023}}</ref> The Central Freeway's northernmost leg in San Francisco was demolished in the early 2000s after it had sustained damage in the [[1989 Loma Prieta earthquake]], which required the upper deck to be removed in 1997.<ref>{{cite news |last=Minton |first=Torri |date=April 12, 1997 |title=S.F. freeway reopening 2 days early |page=A1 |url=https://www.sfgate.com/news/article/PAGE-ONE-S-F-Freeway-Reopening-2-Days-Early-2846258.php |work=San Francisco Chronicle |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807025844/https://www.sfgate.com/news/article/PAGE-ONE-S-F-Freeway-Reopening-2-Days-Early-2846258.php}}</ref> A portion of the corridor was replaced by [[Octavia Boulevard]], which opened in 2005, while US&nbsp;101 was rerouted onto Van Ness Avenue further east.<ref name="google"/><ref>{{cite news |last=King |first=John |date=January 3, 2007 |title=An urban success story: Octavia Boulevard an asset to post-Central Freeway area |page=B1 |url=https://www.sfgate.com/bayarea/place/article/SAN-FRANCISCO-An-urban-success-story-Octavia-2659608.php |work=San Francisco Chronicle |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807025847/https://www.sfgate.com/bayarea/place/article/SAN-FRANCISCO-An-urban-success-story-Octavia-2659608.php}}</ref> From 2016 to 2022, Van Ness Avenue was rebuilt by the [[San Francisco Municipal Railway]] to add center bus lanes and landscaped medians as part of the [[Van Ness Bus Rapid Transit]] project.<ref>{{cite news |last=Cano |first=Ricardo |date=March 25, 2022 |title=It took 27 years and $300 million. Will S.F. Van Ness BRT improve traffic congestion? |url=https://www.sfchronicle.com/sf/article/S-F-s-Van-Ness-transit-project-is-ready-after-17027218.php |work=San Francisco Chronicle |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807025844/https://www.sfchronicle.com/sf/article/S-F-s-Van-Ness-transit-project-is-ready-after-17027218.php}}</ref>

Several existing freeway sections in California were expanded to add [[high-occupancy vehicle lane]]s (HOV lanes) beginning in the 1980s to address increased congestion, especially in the San Francisco Bay Area.<ref>{{cite news |last=Richards |first=Gary |date=February 5, 1995 |title=Bay Area drivers turn the corner on carpooling |page=1A |work=The Mercury News}}</ref><ref>{{cite news |last=Cabanatuan |first=Michael |date=July 13, 2016 |title=Officials try to untangle commute on Hwy. 101 on Peninsula |url=https://www.sfchronicle.com/bayarea/article/8-9-million-shifted-to-begin-studies-of-express-8376933.php |work=San Francisco Chronicle |accessdate=August 6, 2023 |archive-date=August 7, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230807050750/https://www.sfchronicle.com/bayarea/article/8-9-million-shifted-to-begin-studies-of-express-8376933.php}}</ref> By 1984, a section in Marin County had been opened to traffic;<ref>{{cite news |last=Willis |first=Doug |date=February 15, 1984 |title=California freeways of future to be crowded, computerized |page=B1 |work=News-Pilot |agency=Associated Press}}</ref> it was followed by sections in San Mateo and Santa Clara counties that were funded by a sales tax approved in a 1984 ballot measure.<ref>{{cite news |last=Lapin |first=Lisa |date=December 16, 1989 |title=Carpool cheats peeve P.A. leaders |page=B1 |work=The Mercury News}}</ref> The HOV lanes were extended south through San Jose to Bernal Road in 1990.<ref>{{cite news |date=June 8, 1990 |title=Commute crunch eases a bit today |page=B1 |work=The Mercury News}}</ref> A {{convert|16|mi|km|adj=mid}} section of the existing HOV lanes from [[Redwood City, California|Redwood City]] to [[San Bruno, California|San Bruno]] was converted to [[high-occupancy toll lane]]s in 2023 with the use of [[electronic toll collection]].<ref>{{cite news |last=Echeverria |first=Danielle |date=March 6, 2023 |title=New 101 express lanes just opened in this part of the Bay Area. But they'll cost you |url=https://www.sfchronicle.com/bayarea/article/highway-101-toll-express-lanes-17817990.php |work=San Francisco Chronicle |accessdate=February 8, 2024 |archive-date=February 8, 2024 |url-status=live |archive-url=https://web.archive.org/web/20240208080921/https://www.sfchronicle.com/bayarea/article/highway-101-toll-express-lanes-17817990.php}}</ref><ref>{{cite news |last=Cabanatuan |first=Michael |date=November 1, 2022 |title=New Bay Area express lanes on Hwy. 101 are opening. Here's how you can buy your way into them |url=https://www.sfchronicle.com/bayarea/article/new-bay-area-express-lanes-on-hwy-101-are-17547756.php |work=San Francisco Chronicle |accessdate=February 8, 2024 |archive-date=February 8, 2024 |url-status=live |archive-url=https://web.archive.org/web/20240208080920/https://www.sfchronicle.com/bayarea/article/new-bay-area-express-lanes-on-hwy-101-are-17547756.php}}</ref>

[[File:Oregon Coast Highway Washout.jpg|thumb|right|A washed-out section of US&nbsp;101 near [[Newport, Oregon]], in 2013|alt=The remains of an asphalt road that has been destroyed with several pieces lifted up from the ground and others with large cracks.]]

Sections of US&nbsp;101 in Oregon have been rebuilt or relocated due to erosion or landslides that caused considerable damage to the highway.<ref name="OPB-Riprap"/><ref>{{cite news |last=Theen |first=Andrew |date=March 1, 2019 |title='Dramatic' landslide still blocking U.S. 101 north of Brookings |url=https://www.oregonlive.com/commuting/2019/02/dramatic-landslide-still-blocking-us-101-north-of-brookings.html |work=The Oregonian |accessdate=May 4, 2024}}</ref> The use of [[riprap]] to reinforce new sections of the roadway was banned by the [[Oregon Department of Land Conservation and Development]] in 1977 due to its effect on beach degradation. An effort to repeal the ban and rebuild sections of US&nbsp;101 began in 2002 and resulted in an amendment in 2022.<ref name="OPB-Riprap"/><ref name="LCL-Patch">{{cite news |last=Card |first=Steve |date=March 16, 2024 |title=Another patch on the road |url=https://www.newportnewstimes.com/news/another-patch-on-the-road/article_226f0d38-e0c1-11ee-ba02-87b39999b012.html |work=[[Lincoln County Leader]] |location=Newport, Oregon |accessdate=May 4, 2024}}</ref> Several sections of US&nbsp;101 between Newport and Lincoln City are identified as persistent sunken grade and rockfall areas in need of frequent repairs.<ref name="LCL-Patch"/> Other portions of the highway in southwestern Oregon had landslide and subsidence issues, including a section in [[Harbor, Oregon|Harbor]] that was closed for several weeks in early 2016 by an {{convert|80|ft|m|adj=mid}} [[sinkhole]].<ref>{{cite news |last=Chokshi |first=Niraj |date=January 30, 2016 |title=A 'monster' 80-foot sinkhole closed a stretch of coastal highway in Oregon |url=https://www.washingtonpost.com/news/post-nation/wp/2016/01/29/its-a-monster-for-sure-sinkhole-closes-part-of-oregon-highway/ |newspaper=The Washington Post |url-access=subscription |accessdate=May 5, 2024}}</ref><ref>{{cite news |last=Stebbins |first=Jane |date=February 13, 2016 |title=Highway 101 lane reopens as sinkhole fix continues |url=https://infoweb.newsbank.com/apps/news/document-view?p=WORLDNEWS&docref=news/15B0AFD89D45E198&f=basic |work=[[Curry Coastal Pilot]] |location=Brookings, Oregon |via=[[NewsBank]] |accessdate=May 5, 2024}}</ref>

Severe erosion of the highway along the [[Hoh River]] in Washington was addressed through the construction of eight engineered [[logjam]]s by the [[Washington State Department of Transportation]] in 2004. The project redirected the river's flow through the use of dense piles of [[spruce]] logs reinforced by steel piles; the highway previously underwent four emergency repairs in the area that included installation of riprap and other conventional materials.<ref>{{cite news |last=Downing |first=Jim |date=August 16, 2004 |title=Giant logjams built to protect highway |url=https://archive.seattletimes.com/archive/?date=20040816&slug=hoh16m |work=The Seattle Times |accessdate=May 4, 2024}}</ref><ref>{{cite journal |last1=Hall |first1=Megan |last2=Moler |first2=Steve |date=January 2006 |title=Mimicking Mother Nature |url=https://highways.dot.gov/public-roads/januaryfebruary-2006/mimicking-mother-nature |journal=Public Roads |volume=69 |issue=4 |publisher=Federal Highway Administration |accessdate=May 4, 2024}}</ref> US&nbsp;101 was relocated onto an expressway bypass of [[Sequim, Washington]], in August 1999 that replaced a congested route on the city's main street, Washington Avenue. The {{convert|4.4|mi|km|adj=mid}} project cost $40.7&nbsp;million (equivalent to ${{Format price|{{Inflation|US-GDP|40700000|1999}}}} in {{Inflation-year|US-GDP}} dollars){{inflation-fn|US-GDP}} to construct and included the installation of [[warning signal]]s triggered by the presence of nearby [[Roosevelt elk]] wearing [[Wildlife radio telemetry|radio collars]] for tracking.<ref>{{cite news |last=Erb |first=George |date=August 15, 1999 |title=Sequim is ready for traffic bypass operation |url=https://www.bizjournals.com/seattle/stories/1999/08/16/newscolumn1.html |work=[[Puget Sound Business Journal]] |url-access=subscription |accessdate=May 5, 2024}}</ref><ref>{{cite news |last=Egan |first=Timothy |author-link=Timothy Egan |date=January 2, 2001 |title=Elk that call ahead to cross the highway |url=https://www.nytimes.com/2001/01/02/us/sequim-journal-elk-that-call-ahead-to-cross-the-highway.html |work=The New York Times |url-access=limited |accessdate=May 5, 2024}}</ref> The {{convert|15|mi|km|adj=mid}} section of the highway between Port Angeles and Sequim was widened to four lanes in November 2014 following a two-year project to fill the final, {{convert|3.5|mi|km|adj=mid}} gap.<ref>{{cite news |last=Ollikainen |first=Rob |date=November 10, 2014 |title=U.S. Highway 101, now with four lanes open, speeds up local mobility |url=https://www.peninsuladailynews.com/news/u-s-highway-101-now-with-four-lanes-open-speeds-up-local-mobility/ |work=Peninsula Daily News |accessdate=May 5, 2024}}</ref> The {{convert|12|mi|km|adj=mid}} section west of Port Angeles along Lake Crescent was rehabilitated from 2017 to 2019 to repave the roadway and repair structures—among them retaining walls and guardrails.<ref>{{cite news |last=Leach |first=Leah |date=November 29, 2019 |title=Three-year project on Highway 101 comes to a close |url=https://www.peninsuladailynews.com/news/three-year-project-on-highway-101-comes-to-a-close/ |work=Peninsula Daily News |accessdate=May 5, 2024}}</ref>

A {{convert|6|mi|km|adj=mid|spell=in}} freeway bypass of [[Willits, California]], for the Redwood Highway opened in November 2016 at a cost of $460&nbsp;million (equivalent to ${{Format price|{{Inflation|US-GDP|460000000|2015}}}} in {{Inflation-year|US-GDP}} dollars).{{inflation-fn|US-GDP}}<ref>{{cite news |last=Anderson |first=Glenda |date=November 3, 2016 |title=Willits Highway 101 bypass finally opens to traffic |url=https://www.pressdemocrat.com/article/news/willits-highway-101-bypass-finally-opens-to-traffic/ |work=The Press Democrat |accessdate=August 2, 2023 |archive-date=March 16, 2024 |url-status=live |archive-url=https://web.archive.org/web/20240316074055/https://www.pressdemocrat.com/article/news/willits-highway-101-bypass-finally-opens-to-traffic/}}</ref> The bypass was expected to divert away tourists and cause a drop in local [[sales tax]] revenue due to lost traffic.<ref>{{cite news |last=Thomas |first=Eric |date=July 4, 2017 |title=Willits in Mendocino County fights to keep tourists coming back as new freeway bypass threatens business |url=https://abc7news.com/willits-bypass-hidden-freeway-costs-cost/2182455/ |publisher=[[KABC-TV|ABC 7]] |accessdate=August 2, 2023 |archive-date=August 3, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230803060458/https://abc7news.com/willits-bypass-hidden-freeway-costs-cost/2182455/}}</ref> A portion of US&nbsp;101 in the North Bay region near San Francisco, nicknamed the "Novato Narrows", was widened to three lanes with the addition of an HOV lane; construction on the {{convert|5|mi|km|adj=mid}} section began in 2011 and is scheduled to be completed in 2026.<ref>{{cite news |last=Cabantuan |first=Michael |date=July 22, 2022 |title=This traffic-choked section of Highway 101 has been under construction for two decades. Here's when it will wrap up |url=https://www.sfchronicle.com/bayarea/article/This-traffic-choked-section-of-Highway-101-has-17322944.php |work=San Francisco Chronicle |accessdate=July 28, 2023 |archive-date=July 28, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230728082920/https://www.sfchronicle.com/bayarea/article/This-traffic-choked-section-of-Highway-101-has-17322944.php}}</ref> A four-phase widening through the Santa Barbara area to add a third lane in each direction began construction in 2008. Its final phase is estimated to cost $700&nbsp;million and be completed in 2027.<ref>{{cite news |last=Yamamura |first=Jean |date=April 2, 2020 |title=Highway 101 Widening Begins Final Phase in Carpinteria |url=https://www.independent.com/2020/04/02/highway-101-widening-begins-final-phase-in-carpinteria/ |work=[[Santa Barbara Independent]] |accessdate=May 23, 2024}}</ref><ref>{{cite news |last=Barnes |first=Kathryn |date=March 8, 2017 |title=Where is Santa Barbara's commuter train?  |url=https://www.kcrw.com/news/articles/where-is-santa-barbaras-commuter-train |publisher=[[KCRW]] |accessdate=May 23, 2024}}</ref> The world's largest urban [[wildlife crossing]], named the [[Wallis Annenberg Wildlife Crossing]], is under construction over US&nbsp;101 in [[Agoura Hills, California]], and is scheduled to open in 2025.<ref>{{cite news |last=Mossburg |first=Cheri |date=April 26, 2022 |title=Construction starts on world's largest wildlife crossing to let animals roam over 10 lanes of L.A. highway |url=https://www.cnn.com/2022/04/23/us/california-wildlife-crossing-scn-trnd/index.html |publisher=[[CNN]] |accessdate=August 3, 2023 |archive-date=August 4, 2023 |url-status=live |archive-url=https://web.archive.org/web/20230804063938/https://www.cnn.com/2022/04/23/us/california-wildlife-crossing-scn-trnd/index.html}}</ref>

==Major intersections==
;California<ref name="randmcnally">{{cite book |author=Rand McNally |year=2014 |title=The Road Atlas |edition=Walmart |pages=12, 14–15, 84, 108 |publisher=[[Rand McNally]] |location=Chicago |isbn=978-0-528-00771-2}}</ref>
: {{jct|country=USA|I|5}} in [[Los Angeles]]
: {{jct|country=USA|I|10}} in [[Los Angeles]]
: {{jct|state=CA|SR|110|to2=y|I|110}} in Los Angeles
: {{jct|state=CA|SR|134|SR|170}} in Los Angeles
: {{jct|country=USA|I|405|dab1=California}} in Los Angeles
: {{jct|country=USA|I|280|dab1=California|I|680|dab2=California}} in [[San Jose, California|San Jose]]
: {{jct|country=USA|I|880|dab1=California}} in San Jose
: {{jct|state=CA|SR|92}} in San Mateo
: {{jct|country=USA|I|380|dab1=California}} on the [[San Bruno, California|San Bruno]]–[[South San Francisco, California|South San Francisco]] city line
: {{jct|country=USA|I|280|dab1=California}} in [[San Francisco]]
: {{jct|country=USA|I|80}} in San Francisco
:{{jct|state=CA|SR|1}} in San Francisco
: {{jct|country=USA|I|580|dab1=California}} in [[San Rafael, California|San Rafael]]
: {{jct|country=USA|US|199}} near [[Crescent City, California|Crescent City]]
;Oregon<ref name="randmcnally"/>
: {{jct|state=OR|OR|38}} in [[Reedsport, Oregon|Reedsport]]
: {{jct|state=OR|OR|126}} in [[Florence, Oregon|Florence]]
: {{jct|country=USA|US|20}} in [[Newport, Oregon|Newport]]
: {{jct|state=OR|OR|22}} at [[Hebo, Oregon|Hebo]]
: {{jct|country=USA|US|26}} near [[Cannon Beach, Oregon|Cannon Beach]]
: {{jct|country=USA|US|30}} in [[Astoria, Oregon|Astoria]]
;Washington<ref name="randmcnally"/>
: {{jct|state=WA|US-Alt|101}} near [[Ilwaco, Washington|Ilwaco]]
: {{jct|state=WA|SR|4}} near [[Naselle, Washington|Naselle]]
: {{jct|country=USA|US|12}} in [[Aberdeen, Washington|Aberdeen]]
: {{jct|state=WA|SR|20}} at [[Discovery Bay, Washington|Discovery Bay]]
: {{jct|state=WA|SR|3}} near [[Shelton, Washington|Shelton]]
: {{jct|state=WA|SR|8}} near [[Olympia, Washington|Olympia]]
: {{jct|country=USA|I|5}} in [[Tumwater, Washington|Tumwater]]

==See also==
* [[British Columbia Highway 101|BC Highway 101]], a Canadian highway numbered to match US&nbsp;101
* [[Special routes of U.S. Route 101]]

==Notes==
{{reflist|group=lower-alpha}}

==References==
{{reflist}}

==External links==
{{Commons category|U.S. Route 101}}
{{Attached KML|display=title,inline}}
*[http://www.historic101.com/ Historic101.com]
*[http://usends.com/101.html Endpoints of U.S. Highway 101]

{{US Highways}}

{{Authority control}}

[[Category:U.S. Route 101| ]]
[[Category:United States Numbered Highway System|01-1]]