Editing Interstate 15 (section)

==History==
I-15 was constructed along the route of [[U.S. Route 91|US&nbsp;91]]. Once I-15 was relatively intact, US&nbsp;91 was decommissioned, except for one part in Northern Utah&nbsp;/ Southern Idaho where I-15 instead followed the route of former [[U.S. Route 191|US&nbsp;191]].

I-15 originally had two suffixed routes. In California, I-15 had an eastern branch bypassing [[San Bernardino, California|San Bernardino]], which was designated I-15E. I-15E was renumbered and is now [[Interstate 215 (California)|I-215]]. Present day routing of I-15 in California was originally given "I-15W" as its title while it was under construction (the original asphalt portions from Temescal Canyon to Ontario Avenue were dubbed I-15W on maps until 1974), but was never officially signed as such.<ref>{{cite web |url = http://www.interstate-guide.com/i-215_ca.html |archive-url = https://web.archive.org/web/20031011192726/http://www.interstate-guide.com/i-215_ca.html |url-status = dead |archive-date = October 11, 2003 |title = entry for Interstate 215 California |publisher = Interstate-guide.com |access-date = November 27, 2011 }}</ref> In Idaho, I-15 had a western branch near [[Pocatello, Idaho|Pocatello]] that connected I-15 and I-84 (then I-80N). This highway was designated I-15W. It is now the [[Interstate 86 (west)|western I-86]].<ref>{{cite web |url = http://www.interstate-guide.com/i-086_west.html |title = entry for I-86 Western |publisher = Interstate-guide.com |access-date = November 27, 2011 |archive-url = https://web.archive.org/web/20121019125648/http://www.interstate-guide.com/i-086_west.html |archive-date = October 19, 2012 |url-status = dead }}</ref>

===Growth along route===
Since the construction of I-15, California, Nevada, and Utah have consistently ranked in the fastest-growing areas of the United States. As a result, the route of I-15 has substantially increased in population and commuter traffic has increased the traffic burden on the freeway. Current population estimates are that more than 75&nbsp;percent of the population of Utah,<ref name=UTI>{{cite web |url = http://www.utah.com/visitor/state_facts/population.htm |title = Population-Visitor Center- Utah.com |access-date = January 2, 2008 |publisher = Utah Travel Industry |url-status = dead |archive-url = https://web.archive.org/web/20080117034523/http://www.utah.com/visitor/state_facts/population.htm |archive-date = January 17, 2008 |df = mdy-all }}</ref> 19&nbsp;percent of the population of California, and more than 70&nbsp;percent of the population of Nevada live in counties where I-15 is the primary [[Interstate Highway System|Interstate Highway]].

Similarly, in California, I-15 is seeing more commuter traffic due to the growth of the [[Mojave Desert]] communities of [[Hesperia, California|Hesperia]], [[Victorville, California|Victorville]], and [[Barstow, California|Barstow]]. In Utah, I-15 has been under near-constant construction in the [[Wasatch Front]], and future plans released by the [[UDOT|Utah Department of Transportation (UDOT)]] indicate that this will continue in the north ''and'' the far south of the state as well, due to the extremely rapid growth of [[Washington County, Utah|Washington County]] and surrounding areas. In like manner, [[Las Vegas]] in Nevada has seen growth along I-15, and in all of the states that it currently serves, it has recently been or is currently in the process of being widened.<ref name=udot>{{cite web |url = http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:69, |title = Utah Department of Transportation, Projects Under Construction |access-date = January 2, 2008 |publisher = Utah Department of Transportation |archive-date = May 21, 2012 |archive-url = https://web.archive.org/web/20120521232341/http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:69, |url-status = dead }}</ref><ref>{{cite web |url = http://www.nevadadot.com/Projects_and_Programs/Road_Projects/District_1_Construction_Report.aspx |title = District 1 Construction Report |access-date = January 2, 2008 |publisher = Nevada Department of Transportation |archive-url = https://web.archive.org/web/20110527065208/http://www.nevadadot.com/Projects_and_Programs/Road_Projects/District_1_Construction_Report.aspx |archive-date = May 27, 2011 |url-status = dead }}</ref><ref>{{cite web |url = http://www.dot.ca.gov/dist8/projects/15/I-15%20Brstw%20-STLN.revsd%206-2004%20copy.pdf |title = Interstate 15 Major Improvements |publisher = California Department of Transportation |url-status = dead |archive-url = https://web.archive.org/web/20070615184246/http://www.dot.ca.gov/dist8/projects/15/I-15%20Brstw%20-STLN.revsd%206-2004%20copy.pdf |archive-date = June 15, 2007 }}</ref> The portions in Arizona, Idaho and Montana have retained their rural, long-haul character. Although Arizona has also grown substantially since the construction of I-15, this [[highway]] serves only the [[Arizona Strip|isolated corner]] of northwestern Arizona.

Due to this rapid area growth, the I-15 corridor is the focus of several [[mass transit]] projects. The [[Las Vegas Monorail]], ''[[FrontRunner]]'' [[Commuter rail in North America|commuter rail]] system, and [[TRAX (light rail)|TRAX]] [[light rail]] in [[Salt Lake City]] are mass transit lines loosely parallel to I-15 that are now in operation.{{cn|date=June 2024}}

The Los Angeles–Las Vegas corridor has long been proposed as a high-speed [[Magnetic levitation train|maglev train]] route to relieve highway congestion. Proposals from as early as the 1970s were succeeded by the [[California–Nevada Interstate Maglev]] project, which was studied from 2004 to 2010 but never realized.<ref name="KTNV-Trains">{{cite news |last=Lupiani |first=Joyce |date=April 1, 2021 |title=History of train service between Las Vegas and California |url=https://www.ktnv.com/vegastrainhistory |publisher=[[KTNV-TV|KTNV]] |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053959/https://www.ktnv.com/vegastrainhistory |url-status=live }}</ref><ref>{{cite news |last=Velotta |first=Richard N. |date=March 3, 2024 |title=Before the LV-to LA rail project, maglev was planned |url=https://www.reviewjournal.com/business/business-columns/inside-gaming/before-the-lv-to-la-rail-project-maglev-was-planned-3010776/ |work=Las Vegas Review-Journal |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053943/https://www.reviewjournal.com/business/business-columns/inside-gaming/before-the-lv-to-la-rail-project-maglev-was-planned-3010776/ |url-status=live }}</ref> [[Amtrak]] ran a conventional passenger rail service between the two cities, named the ''[[Desert Wind]]'', from 1979 to 1997.<ref name="KTNV-Trains"/> The [[Brightline West]] line, a conventional [[high-speed rail]] service under a private operator, broke ground in 2024 and is scheduled to commence in 2028 with service between [[Rancho Cucamonga, California|Rancho Cucamonga]] and Las Vegas.<ref>{{cite news |last=Encinas |first=Amaris |date=April 23, 2024 |title=Brightline West broke ground, now the high-speed train is on the clock for 2028 Olympics |url=https://www.usatoday.com/story/travel/news/2024/04/23/brightline-west-train-route-map/73428402007/ |work=USA Today |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053958/https://www.usatoday.com/story/travel/news/2024/04/23/brightline-west-train-route-map/73428402007/ |url-status=live }}</ref> It will use the median of I-15 for most of its {{convert|218|mi|km|adj=mid}} route and reach speeds of up to {{convert|186|mph|kph}}.<ref>{{cite news |date=January 23, 2024 |title=Feds OK $2.5 billion more for high-speed rail from SoCal to Las Vegas; could open by 2028 |url=https://www.desertsun.com/story/news/nation/california/2024/01/23/high-speed-rail-from-las-vegas-to-southern-california-may-open-by-2028/72326897007/ |work=Desert Sun |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053943/https://www.desertsun.com/story/news/nation/california/2024/01/23/high-speed-rail-from-las-vegas-to-southern-california-may-open-by-2028/72326897007/ |url-status=live }}</ref>