Editing Jefferson County, Colorado

{{short description|County in Colorado, United States}}
{{Use mdy dates|date=December 2024}}
{{Use American English|date=July 2022}}
{{Infobox U.S. county
 | county     = Jefferson County
 | state              = Colorado
 | flag                 = Flag of Jefferson County, Colorado.svg
 | seal                 = Seal of Jefferson County, Colorado.svg
 | founded date     = November 1
 | founded year         = 1861
 | seat wl             = Golden
 | largest city wl    = Lakewood
 | area_total_sq_mi     = 774
 | area_land_sq_mi      = 764
 | area_water_sq_mi     = 9.8
 | area percentage      = 1.3
 | census yr            = 2020
 | pop                  = 582910
 | pop_est_as_of        = 2023
 | population_est       = 576366 {{loss}}
 | density_sq_mi        = auto
 | web                  = www.jeffco.us
 | named for            = [[Jefferson Territory]]
 | footnotes            = 
 | ex image             = JeffersonCountyCO Courthouse 01Oct2017.jpg
 | ex image cap         = Jefferson County Courthouse in Golden, nicknamed "Colorado's Taj Mahal" for its dome architecture
 | district             = 1st
 | district2            = 2nd
 | district3            = 6th
 | district4            = 7th
 | time zone          = Mountain
 | motto                = Gateway to the Rocky Mountains
}}

'''Jefferson County''' is a [[county]] located in the [[U.S. state]] of [[Colorado]]. As of the [[2020 United States census|2020 census]], the population was 582,910,<ref name="2020Census">{{cite web|title=State & County QuickFacts|url=https://www.census.gov/quickfacts/fact/table/jeffersoncountycolorado/PST045219|publisher=United States Census Bureau|access-date=September 5, 2021}}</ref> making it the fourth-most populous county in Colorado. The [[county seat]] is [[Golden, Colorado|Golden]],<ref name="GR6">{{cite web|url=http://www.naco.org/Counties/Pages/FindACounty.aspx|access-date=June 7, 2011|title=Find a County|publisher=National Association of Counties|url-status=dead|archive-url=https://web.archive.org/web/20110531210815/http://www.naco.org/Counties/Pages/FindACounty.aspx|archive-date=May 31, 2011}}</ref> and the most populous city is [[Lakewood, Colorado|Lakewood]].

Jefferson County is included in the [[Denver]]-[[Aurora, Colorado|Aurora]]-Lakewood, CO [[Denver-Aurora-Lakewood, CO Metropolitan Statistical Area|Metropolitan Statistical Area]]. Located along the [[Front Range]] of the [[Rocky Mountains]], Jefferson County is adjacent to the state capital of Denver.

In 2010, the center of population of Colorado was located in Jefferson County.<ref>{{cite web|title=Centers of Population by State: 2010|url=https://www.census.gov/geo/reference/docs/cenpop2010/CenPop2010_Mean_ST.txt|publisher=United States Census Bureau|access-date=June 8, 2014|url-status=dead|archive-url=https://web.archive.org/web/20140103082820/http://www.census.gov/geo/reference/docs/cenpop2010/CenPop2010_Mean_ST.txt|archive-date=January 3, 2014}}</ref>

The county's slogan is the "Gateway to the Rocky Mountains", and it is commonly nicknamed [[Jeffco (disambiguation)|Jeffco]]. The name Jeffco is incorporated in the name of the Jeffco School District, the Jeffco Business Center Metropolitan District No. 1, and several businesses located in Jefferson County. Jeffco is also incorporated in the unofficial monikers of many Jefferson County agencies. The [[Rocky Mountain Metropolitan Airport]] operated by Jefferson County was previously known as the Jeffco Airport.

A major employer in Jefferson County is the large [[Coors Brewing Company]] in Golden. Also, the state-supported [[Colorado School of Mines]], a university specializing in [[mining]], [[geology]], [[chemistry]], and [[engineering]] is located in Jefferson County.

==History==
On August 25, 1855, the [[Kansas Legislature|Kansas Territorial Legislature]] created [[Arapahoe County, Kansas Territory|Arapahoe County]] to govern the entire western portion of the [[Territory of Kansas|territory]]. The county was named for the [[Arapaho Nation]] of [[Native Americans in the United States|Native Americans]] who lived in the region.

In June 1858, [[gold]] was discovered along the [[South Platte River]] in [[Arapahoe County, Kansas Territory|Arapahoe County]] (in present-day [[Englewood, Colorado|Englewood]]) by [[William Greeneberry Russell]] and Sam Bates who had been following up the June 22, 1850, discovery of gold on Ralston Creek in today's Jefferson County by Lewis Ralston, for whom the creek was named. This discovery precipitated the [[Pike's Peak Gold Rush]]. The Doniphan Party upon arriving upon Clear Creek discovered markers left over from earlier mining in 1834 by the Estes Party, placed their own alongside and on November 29, 1858, founded the future county's first town of Arapahoe City upon the land southeast of today's West 44th Avenue and McIntyre Street (with West 44th running through the town).<ref>{{cite web|url=https://www.jeffco.us/DocumentCenter/View/9478/Historically-Jeffco-2011-PDF |title=Historically Jeffco 2011|publisher=Jefferson County Historical Commission|date=2011|access-date=February 25, 2024}}</ref> On June 16, 1859, its second town, [[Golden, Colorado]], was founded in the valley to the west. Many residents of the mining region felt disconnected from the remote territorial governments of [[Territory of Kansas|Kansas]] and [[Territory of Nebraska|Nebraska]], so they voted to form their own [[Territory of Jefferson]] on October 24, 1859. The following month on November 28, 1859, the Jefferson Territorial Legislature organized 12 counties for the new territory, including [[Jefferson County, Jefferson Territory|Jefferson County]]. Jefferson County was named for the namesake of the Jefferson Territory, [[Thomas Jefferson]], the principal author of the [[United States Declaration of Independence|Declaration of Independence]] and the nation's third [[President of the United States|president]].<ref>{{cite book | url=https://archive.org/details/bub_gb_9V1IAAAAMAAJ | title=The Origin of Certain Place Names in the United States | publisher=Govt. Print. Off. | author=Gannett, Henry | year=1905 | pages=[https://archive.org/details/bub_gb_9V1IAAAAMAAJ/page/n167 168]}}</ref>  [[Golden, Colorado Territory|Golden City]] was elected on January 2, 1860, as the [[county seat]] of Jefferson County.  [[Robert Williamson Steele]], [[Governor]] of the [[Provisional Government of the Territory of Jefferson]] from 1859 to 1861, built his home in the county at [[Mount Vernon, Colorado|Mount Vernon]] and later at [[Apex, Colorado|Apex]]. Originally Jefferson County's borders extended to the [[40th parallel north]], the [[South Platte River]] (excluding the town of Highland) to the east, and to Bear Creek to the south.

The Jefferson Territory never received federal sanction, but during his last week in office, [[U.S. President|President]] [[James Buchanan]] signed an act which organized the [[Territory of Colorado]] on February 28, 1861.<ref name=ColoradoTerritory>{{cite web|url=http://www.colorado.gov/dpa/doit/archives/territory.pdf |archive-url=https://web.archive.org/web/20041025191401/http://www.colorado.gov/dpa/doit/archives/territory.pdf |archive-date=October 25, 2004 |url-status=live|title=An Act to provide a temporary Government for the Territory of Colorado|publisher=[[Thirty-sixth United States Congress]]|date=February 28, 1861|access-date=November 26, 2007}}</ref>  That November 1, the new [[Colorado General Assembly]] organized the 17 original counties of Colorado, including Jefferson County. The reorganized Jefferson County extended to most of its current borders and Golden continued as county seat. In 1908, the southern tip of Jefferson County was transferred to [[Park County, Colorado|Park County]], reducing Jefferson County to its present length of {{convert|54|mi|km}}. Several annexations by the [[Denver, Colorado|City & County of Denver]] and the 2001 consolidation of the [[Broomfield, Colorado|City & County of Broomfield]] removed the east and extreme northeastern corner of the county, respectively.

==Geography==
[[File:Long Scraggy Peak.JPG|250px|thumb|right|Long Scraggy Peak in the southeastern part of the county.]]
At the [[2020 United States census]], the county had a total area of {{convert|774|sqmi}}, of which {{convert|764|sqmi}} is land and {{convert|9.8|sqmi}} (1.3%) is water.<ref name="GR1">{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html|publisher=[[United States Census Bureau]]|access-date=April 23, 2011|date=February 12, 2011|title=US Gazetteer files: 2010, 2000, and 1990}}</ref> As of April 1, 2020, the mean population center<ref name=Popcenters>{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/centers-population.html|title=Centers of Population|publisher=[[United States Census Bureau]]|access-date=January 5, 2025}}</ref> of the State of Colorado was located in Jefferson County at coordinates {{coord|39.5347|-105.1854|type:event_region:US-CO_source:USCB|date=April 1, 2020|display=inline|name=2020 mean population center of the State of Colorado}}<ref name=Stpopcenters>{{cite web|url=https://www2.census.gov/geo/docs/reference/cenpop2020/CenPop2020_Mean_ST.txt|title=Centers of Population by State: 2020|publisher=[[United States Census Bureau]]|access-date=January 5, 2025}}</ref> near the (ironically) tiny hamlet of Phillipsburg.

===Adjacent counties===
Jefferson County is one of the few counties in the United States to border as many as ten counties.

{{div col}}
*[[Boulder County, Colorado|Boulder County]] – north
*[[Broomfield, Colorado|City and County of Broomfield]] – northeast
*[[Adams County, Colorado|Adams County]] – east
*[[Denver|City and County of Denver]] – east
*[[Arapahoe County, Colorado|Arapahoe County]] – east
*[[Douglas County, Colorado|Douglas County]] – east
*[[Teller County, Colorado|Teller County]] – south
*[[Park County, Colorado|Park County]] – southwest
*[[Clear Creek County, Colorado|Clear Creek County]] – west
*[[Gilpin County, Colorado|Gilpin County]] – northwest
{{div col end}}

===Major highways===
* [[File:I-70 (CO).svg|20px]] [[Interstate 70 (Colorado)|Interstate 70]]
*{{jct|state=CO|BS|70|dab1=Denver}}
* [[File:US 6.svg|20px]] [[U.S. Highway 6 (Colorado)|U.S. Highway 6]]
* [[File:US 40.svg|20px]] [[U.S. Highway 40 (Colorado)|U.S. Highway 40]]
* [[File:US 285.svg|20px]] [[U.S. Highway 285 (Colorado)|U.S. Highway 285]]
* [[File:Colorado 8.svg|20px]] [[Colorado State Highway 8|State Highway 8]]
* [[File:Colorado 58.svg|20px]] [[Colorado State Highway 58|State Highway 58]]
* [[File:Colorado 72.svg|20px]] [[Colorado State Highway 72|State Highway 72]]
* [[File:Colorado 74.svg|20px]] [[Colorado State Highway 74|State Highway 74]]
* [[File:Colorado 75.svg|20px]] [[Colorado State Highway 75|State Highway 75]]
* [[File:Colorado 93.svg|20px]] [[Colorado State Highway 93|State Highway 93]]
* [[File:Colorado 121.svg|20px]] [[Colorado State Highway 121|State Highway 121]]
* [[File:Colorado 391.svg|20px]] [[Colorado State Highway 391|State Highway 391]]
* [[File:Colorado 470.svg|20px]] [[Colorado State Highway 470|State Highway 470]]
* [[Chatfield Ave]]
* [[44th Ave]]

===Recreational areas===
{{div col|colwidth=15em}}
*Alderfer/Three Sisters Park
*Apex Park
*Bear Creek Lake Park
*[[Centennial Cone|Centennial Cone Park]]
*Clear Creek Canyon Park
*Coal Creek Canyon
*[[Crown Hill Park]]
*Deer Creek Canyon Park
*[[Elk Meadow Park]]
*Evergreen Lake
*Fairmount Trail
*Flying J Ranch Park
*Hildebrand Ranch Park
*[[Hiwan Homestead Museum]]
*Lair o' the Bear Park
*Lewis Meadows Park
*Lookout Mountain Nature Center
*Matthews/Winters Park
*Meyer Ranch Park
*Mount Falcon Park
*Mount Galbraith Park
*Mount Glennon
*[[Mount Lindo]]
*North Table Mountain Park
*Pine Valley Ranch Park
*Ranson/Edwards Homestead Ranch
*Reynolds Park
*Sister City Park
*South Table Mountain Park
*[[South Valley Park]]
*Standley Lake Regional Park
*Van Bibber Park
*Welchester Tree Grant Park
*White Ranch Park
*Windy Saddle Park
*Urban Trails
{{div col end}}

==Demographics==
{{US Census population
|1870= 2390
|1880= 6804
|1890= 8450
|1900= 9306
|1910= 14231
|1920= 14400
|1930= 21810
|1940= 30725
|1950= 55687
|1960= 127520
|1970= 233031
|1980= 371753
|1990= 438430
|2000= 527056
|2010= 534543
|2020= 582910
|estyear=2023
|estimate=576366
|estref=<ref name="USCensusEst2023">{{cite web|url=https://www.census.gov/programs-surveys/popest/data/tables.html|title=Annual Estimates of the Resident Population for Counties: April 1, 2020 to July 1, 2023|publisher=United States Census Bureau|access-date=March 31, 2024}}</ref>
|align-fn=center
|footnote=U.S. Decennial Census<ref>{{cite report |title=U.S. Decennial Census |publisher=[[United States Census Bureau]] |url=https://www.census.gov/programs-surveys/decennial-census.html |access-date=June 8, 2014}}</ref><br/>
1790-1960<ref>{{cite report |title=Historical Census Browser |publisher=[[University of Virginia]] |department=UVA Libraries |url=http://mapserver.lib.virginia.edu |access-date=June 8, 2014}}</ref> 1900-1990<ref>{{cite report |title=Population of Counties by Decennial Census: 1900 to 1990 |publisher=[[United States Census Bureau]] |url=https://www.census.gov/population/cencounts/co190090.txt |access-date=June 8, 2014}}</ref><br/>
1990-2000<ref>{{cite report |series=Census 2000 |id=PHC-T-4 |title=Ranking Tables for Counties: 1990 and 2000 |publisher=[[United States Census Bureau]] |url=https://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-url=https://web.archive.org/web/20100327165705/http://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-date=March 27, 2010 |url-status=live |access-date=June 8, 2014}}</ref> 2010-2020<ref name=2020Census />
}}

As of the [[census]]<ref name=GR8>{{cite web |publisher=[[United States Census Bureau]] |title=U.S. Census |type=main website |url=https://www.census.gov |access-date=May 14, 2011}}</ref> of 2000, there were 527,056&nbsp;people, 206,067&nbsp;households, and 140,537&nbsp;families residing in the county. The [[population density]] was {{convert|683|/mi2|/km2|disp=preunit|people&nbsp;|people}}. There were 212,488&nbsp;housing units at an average density of {{convert|275|/mi2|/km2|disp=preunit|people&nbsp;|people}}. The racial makeup of the county was
:{|
|-
| {{right|90.59%}} || <!-- kludge margin --> || [[Race (United States Census)|White]] 
|-
| {{right|0.89%}} || || [[Race (United States Census)|Black]] or [[Race (United States Census)|African American]] 
|-
| {{right|0.75%}} || || [[Race (United States Census)|Native American]] 
|-
| {{right|2.28%}} || || [[Race (United States Census)|Asian]] 
|-
| {{right|0.08%}} || || [[Race (United States Census)|Pacific Islander]] 
|-
| {{right|3.23%}} || || from [[Race (United States Census)|other races]] 
|-
|colspan="3"| {{center| 9.95% of the population were either [[Race (United States Census)|Hispanic]] or [[Race (United States Census)|Latino]] of any race}}
|-
|colspan="3"| {{center| 2.18% in two or more races }}
|}

There were 206,067&nbsp;households, out of which 33.40% had children under age&nbsp;18 living with them, 55.10% were [[Marriage|married couples]] living together, 9.10% had a female householder with no husband present, and 31.80% were non-families. 24.50% of all households were made up of individuals, of those 6.30% were someone living alone who was 65&nbsp;years of age or older. The average household size was 2.52, and the average family size was 3.03&nbsp;persons.

In the county, the population ages were spread out:
:{|
|-
| {{right|25.30%}} || <!-- kludge margin --> || under age&nbsp;18
|-
| {{right|8.10%}} || || aged&nbsp;18–24
|-
| {{right|32.10%}} || || aged&nbsp;25–44
|-
| {{right|24.90%}} || || aged&nbsp;45–64
|-
| {{right|9.60%}} || || 65&nbsp;years of age or older
|-
|colspan="3"| {{center|The median age was 37&nbsp;years.}}

|}

For every 100&nbsp;females there were 99.00&nbsp;males. For every 100&nbsp;females age&nbsp;18 and over, there were 96.80&nbsp;males.

The median income for a household in the county was $57,339, and the median income for a family was $67,310. Males had a median income of $45,306 versus $32,372 for females. The [[per capita income]] for the county was $28,066. About 3.40% of families and 5.20% of the population were below the [[poverty line]], including 5.80% of those under age 18, and 5.10% of those age&nbsp;65 or over.

According to a report in the [[Journal of the American Medical Association|JAMA]], residents of Jefferson County had a 2014 life expectancy of 80.02&nbsp;years.<ref>
{{cite journal
 |last=Dwyer-Lindgren |first=Laura
 |date=May 8, 2017
|title=Inequalities in life expectancy among U.S. counties, 1980 to 2014
 |journal=JAMA Internal Medicine
 |volume=177 |issue=7 |pages=1003–1011
 |doi=10.1001/jamainternmed.2017.0918 |pmc=5543324 |pmid=28492829
}}
</ref>

==Education==
The sole school district serving the county is [[Jefferson County School District R-1]].<ref>{{cite web|url=https://www2.census.gov/geo/maps/DC2020/PL20/st08_co/schooldistrict_maps/c08059_jefferson/DC20SD_C08059.pdf |archive-url=https://web.archive.org/web/20220720015026/https://www2.census.gov/geo/maps/DC2020/PL20/st08_co/schooldistrict_maps/c08059_jefferson/DC20SD_C08059.pdf |archive-date=July 20, 2022 |url-status=live|title=2020 CENSUS - SCHOOL DISTRICT REFERENCE MAP: Jefferson County, CO|publisher=[[U.S. Census Bureau]]|accessdate=July 19, 2022}} – [https://www2.census.gov/geo/maps/DC2020/PL20/st08_co/schooldistrict_maps/c08059_jefferson/DC20SD_C08059_SD2MS.txt Text list]</ref>

;Private schools:
* [[Colorado Academy]]

;Higher Education:
* [[Colorado Christian University]]
* [[Colorado School of Mines]]
* [[Red Rocks Community College]]
* [[Rocky Mountain College of Art and Design]]

[[Jefferson County Public Library]] is the county library system.

==Government and infrastructure==
*The [[Federal Correctional Institution, Englewood]] is in [[unincorporated area|unincorporated]] Jefferson County.<ref>"[http://www.bop.gov/DataSource/execute/dsFacilityAddressLoc?start=y&facilityCode=eng FCI Englewood Contact Information] {{Webarchive|url=https://web.archive.org/web/20130221115050/http://www.bop.gov/DataSource/execute/dsFacilityAddressLoc?start=y&facilityCode=eng |date=February 21, 2013 }}." [[Federal Bureau of Prisons]]. Retrieved on July 28, 2010.</ref>
*The [[Rocky Flats Plant]] produced nuclear weapons in Jefferson County from 1952 until 1989.
*The [[Jefferson County Public Library]], established in 1952.
*The [[Jefferson County Government Center]], also known as the "courts and admin building".
*The [[Denver Federal Center]], the largest concentration of federal government agencies outside of [[Washington, D.C.]], is located in Lakewood.

=== Government ===
The Board of County Commissioners operates as the governing body of the county. Established in 1861, the board consists of three commissioners who are elected [[at-large]] to four-year terms. The board sets policies that guide county programs and operations which serves residents and businesses. There are several elected officials that oversee a department or aspect of county operations.<ref name=":0">{{Cite web |title=Leadership {{!}} Jefferson County, CO |url=https://www.jeffco.us/2078/Leadership |access-date=November 1, 2023 |website=www.jeffco.us}}</ref>
{| class="wikitable sortable"
|+Board of County Commissioners<ref name=":0" /><ref name=":1">{{Cite web |title=Jefferson County Elected Officials |url=https://www.jeffcodems.org/jefferson-county-1 |access-date=November 1, 2023 |website=Jefferson County Democratic Party |language=en-US}}</ref> 
!District
!Commissioner
!Party
|-
|District 1
|Rachel Zenzinger
|Democratic
|-
|District 2
|Andy Kerr
|Democratic
|-
|District 3
|Lesley Dahlkemper
|Democratic
|}
{| class="wikitable sortable"
|+Elected County Officials<ref name=":0" /><ref name=":1" />
!Title
!Official
!Party
|-
|Assessor 
|Scot Kersgaard
|Democratic
|-
|Clerk and Recorder
|Amanda Gonzalez
|Democratic
|-
|Coroner
|Dr. Annette Cannon
|Democratic
|-
|Sheriff
|Regina "Reggie" Marinelli
|Democratic
|-
|Surveyor 
|Robert Hennessy
|Republican<ref>{{Cite web |title=Republican Party Officials - Jefferson County Republican Party |url=https://jeffcorepublicans.com/officials-candidates/ |access-date=November 1, 2023 |website=Jefferson County Republicans |language=en-US}}</ref>
|-
|Treasurer 
|Gerald "Jerry" DiTullio
|Democratic
|}

Jefferson County lies within the 1st Judicial District which is represented by District Attorney Alexis King.<ref>{{cite web | title=DA Alexis King — Colorado First Judicial District Attorney's Office | url=https://firstda.co/who-we-are/da-alexis-king/ | access-date=October 13, 2024 }}</ref>

=== Sheriff's office ===
The Jefferson County Sheriff is an oldest elective office in Jefferson County (along with Clerk and Recorder, Assessor and Treasurer) and among the first popularly elected offices in Colorado, established in 1859 with the first Sheriff, Walter Pollard, elected on January 2, 1860.<ref>{{Cite news|title=The Western Mountaineer|date=January 11, 1860|via=www.coloradohistoricnewspapers.org}}</ref> Its office holders over the course of over 150 years have included some of the most noted law enforcement officers in Colorado history.

The Jefferson County Sheriff's Office responded to the 1999 [[Columbine High School massacre]], and investigated it together with the [[F.B.I.]] The Sheriff's Office received backlash after it was revealed the agency had the perpetrators [[Eric Harris and Dylan Klebold]] in and out of custody prior to the shooting. After the shooting [[Sue Klebold]] sued the Sheriff's office for failing to prevent their son from carrying out the Columbine High shootings. According to a "notice of intent to sue" filed by Susan and Thomas Klebold, county officials were "reckless, willful and wanton" in the way they handled a 1998 police report about Eric Harris' Internet ravings.<ref>{{cite web|url=http://www.acolumbinesite.com/dylan/kleboldfamilytosue.htm|title = Klebold family plans to sue Jeffco}}</ref><ref>{{cite web|url=http://edition.cnn.com/2001/LAW/11/27/columbine.lawsuit/ |title=Judge dismisses all but one Columbine lawsuit  |publisher=[[CNN]] |date=November 27, 2001 |accessdate=May 9, 2022}}</ref><ref>{{cite web | url = http://cjonline.com/stories/041900/new_columbine.shtml | title = Parents sue JeffCo | accessdate = May 9, 2017}}</ref>
This lawsuit was dismissed along with several others pertaining to the shooting.<ref>{{cite web|title=Judge dismisses all but one Columbine lawsuit |date=November 27, 2001|url=http://edition.cnn.com/2001/LAW/11/27/columbine.lawsuit/|access-date=December 19, 2021|website=[[CNN]]}}</ref>

The current county sheriff is Regina "Reggie" Marinelli.<ref>{{Cite web |date=January 10, 2023 |title=Jefferson County Sheriff Regina Marinelli officially steps into new role - CBS Colorado |url=https://www.cbsnews.com/colorado/news/jefferson-county-sheriff-regina-marinelli-oath-office/ |access-date=November 1, 2023 |website=www.cbsnews.com |language=en-US}}</ref> She was elected in 2022 and became the first woman to do so in county history and became the first Democrat to hold the office in nearly a century. She previously worked in the county Sheriff's Office for over 30 years.<ref>{{Cite web |last=Leary |first=Jaime |date=November 15, 2022 |title=Jefferson County Sheriff-elect Regina Marinelli is first woman to lead the agency, and first Democrat in almost a century |url=https://www.cbsnews.com/colorado/news/regina-marinelli-jefferson-county-sheriff-first-woman-lead-agency-democrat/ |access-date=November 1, 2023 |website=CBS Colorado |language=en-US}}</ref>

===Politics===
Jefferson County was a Republican stronghold for most of the 20th century, voting Republican in all but one presidential election between 1940 and 2004. However, it has voted Democratic in every presidential election since 2008, consistent with the general trend in the Denver metropolitan area. In [[2024 United States presidential election in Colorado|2024]], [[Kamala Harris]] won the largest percentage for a Democratic presidential candidate since [[1916 United States presidential election in Colorado|1916]].

{{PresHead|place=Jefferson County, Colorado|source=<ref>{{cite web|url=http://uselectionatlas.org/RESULTS/|title=Dave Leip's Atlas of U.S. Presidential Elections|first=David|last=Leip|website=uselectionatlas.org|access-date=November 26, 2020}}</ref>}}
<!-- PresRow should be {{PresRow|Year|Winning party|GOP vote #|Dem vote #|3rd party vote #|State}} -->
{{PresRow|2024|Democratic|140,505|210,875|10,336|Colorado}}
{{PresRow|2020|Democratic|148,417|218,396|10,545|Colorado}}
{{PresRow|2016|Democratic|138,177|160,776|29,930|Colorado}}
{{PresRow|2012|Democratic|144,197|159,296|7,559|Colorado}}
{{PresRow|2008|Democratic|131,628|158,158|5,282|Colorado}}
{{PresRow|2004|Republican|140,644|126,558|4,366|Colorado}}
{{PresRow|2000|Republican|120,138|100,970|14,383|Colorado}}
{{PresRow|1996|Republican|101,517|89,494|18,712|Colorado}}
{{PresRow|1992|Republican|82,705|80,834|59,664|Colorado}}
{{PresRow|1988|Republican|110,820|81,824|3,867|Colorado}}
{{PresRow|1984|Republican|124,496|53,700|2,432|Colorado}}
{{PresRow|1980|Republican|97,008|41,525|24,078|Colorado}}
{{PresRow|1976|Republican|87,080|52,782|4,211|Colorado}}
{{PresRow|1972|Republican|80,082|31,555|2,960|Colorado}}
{{PresRow|1968|Republican|50,847|31,392|7,118|Colorado}}
{{PresRow|1964|Democratic|33,398|43,162|252|Colorado}}
{{PresRow|1960|Republican|34,105|22,962|137|Colorado}}
{{PresRow|1956|Republican|25,398|14,270|197|Colorado}}
{{PresRow|1952|Republican|19,971|11,509|194|Colorado}}
{{PresRow|1948|Republican|9,903|9,145|260|Colorado}}
{{PresRow|1944|Republican|9,815|7,277|68|Colorado}}
{{PresRow|1940|Republican|8,780|7,745|100|Colorado}}
{{PresRow|1936|Democratic|5,271|7,283|271|Colorado}}
{{PresRow|1932|Democratic|5,522|6,023|503|Colorado}}
{{PresRow|1928|Republican|6,754|2,880|141|Colorado}}
{{PresRow|1924|Republican|4,869|1,271|1,505|Colorado}}
{{PresRow|1920|Republican|3,593|1,941|306|Colorado}}
{{PresRow|1916|Democratic|2,040|3,368|166|Colorado}}
{{PresRow|1912|Democratic|1,011|2,309|2,037|Colorado}}
{{PresRow|1908|Republican|2,623|2,583|193|Colorado}}
{{PresRow|1904|Republican|2,903|1,739|136|Colorado}}
{{PresRow|1900|Democratic|1,807|2,138|89|Colorado}}
{{PresRow|1896|Democratic|300|3,176|93|Colorado}}
{{PresRow|1892|Populist|792|0|1,056|Colorado}}
{{PresRow|1888|Republican|970|767|96|Colorado}}
{{PresRow|1884|Republican|845|743|70|Colorado}}
{{PresFoot|1880|Republican|832|790|57|Colorado}}
{{clear}}

==Recreation==

===State parks===
*[[Chatfield State Park]]
*[[Golden Gate Canyon State Park]]
*[[Staunton State Park]]

===National forests and wilderness===
*[[Pike National Forest]]
*[[Roosevelt National Forest]]
*[[Lost Creek Wilderness]]

===National wildlife refuges===
*[[Rocky Flats National Wildlife Refuge]]
*[[Two Ponds National Wildlife Refuge]]

===Historic trail===
*[[South Platte Trail]]

===Recreational trails===
*[[American Discovery Trail]]
*[[Apex National Recreation Trail]]
*[[Big Dry Creek National Recreation Trail]]
*[[Colorado Trail]]
*[[Platte River Greenway National Recreation Trail]]
*[[Two Ponds National Recreation Trail]]

===Scenic byway===
*[[Lariat Loop Scenic and Historic Byway]]

===Golf course===
*[[Hiwan Golf Club]]
*[[Indian Tree Golf Club]]

==Communities==
===Cities===
{{div col}}
*[[Arvada, Colorado|Arvada]] (part)
*[[Edgewater, Colorado|Edgewater]]
*[[Golden, Colorado|Golden]]
*[[Lakewood, Colorado|Lakewood]]
*[[Littleton, Colorado|Littleton]] (part)
*[[Westminster, Colorado|Westminster]] (part)
*[[Wheat Ridge, Colorado|Wheat Ridge]]
{{div col end}}

===Towns===
{{div col}}
*[[Bow Mar, Colorado|Bow Mar]] (part)
*[[Lakeside, Colorado|Lakeside]]
*[[Morrison, Colorado|Morrison]]
*[[Mountain View, Colorado|Mountain View]]
*[[Superior, Colorado|Superior]] (part)
{{div col end}}

===Census-designated places===
{{div col|colwidth=15em}}
*[[Applewood, Colorado|Applewood]]
*[[Aspen Park, Colorado|Aspen Park]]
*[[Brook Forest, Colorado|Brook Forest]]
*[[Coal Creek, Boulder County, Colorado|Coal Creek]] (part)
*[[Columbine, Colorado|Columbine]]
*[[Dakota Ridge, Colorado|Dakota Ridge]]
*[[East Pleasant View, Colorado|East Pleasant View]]
*[[Evergreen, Colorado|Evergreen]]
*[[Fairmount, Colorado|Fairmount]]
*[[Genesee, Colorado|Genesee]]
*[[Idledale, Colorado|Idledale]]
*[[Indian Hills, Colorado|Indian Hills]]
*[[Ken Caryl, Colorado|Ken Caryl]]
*[[Kittredge, Colorado|Kittredge]]
*[[West Pleasant View, Colorado|West Pleasant View]]
{{div col end}}

===Unincorporated communities===
{{div col}}
*[[Buffalo Creek, Colorado|Buffalo Creek]]
*[[Conifer, Colorado|Conifer]]
*[[Foxton, Colorado|Foxton]]
*[[Pine, Colorado|Pine]]
*[[Pine Junction, Colorado|Pine Junction]]
*[[Plastic, Colorado|Plastic]]
{{div col end}}

==See also==
{{portal|Government|History|Mountains|United States|Colorado}}
*[[Bibliography of Colorado]]
*[[Geography of Colorado]]
*[[History of Colorado]]
**[[Arapahoe County, Kansas Territory]]
**[[National Register of Historic Places listings in Jefferson County, Colorado]]
*[[Index of Colorado-related articles]]
*[[List of Colorado-related lists]]
**[[List of counties in Colorado]]
**[[List of statistical areas in Colorado]]
*[[Outline of Colorado]]
**[[Front Range Urban Corridor]]
{{clear}}

==References==
{{reflist|30em}}

==External links==
{{sister project links|auto=yes}}

*[http://www.jeffco.us/ Jefferson County Government website]
*[https://web.archive.org/web/20070205102713/http://www.stanwyck.com/cogenweb/cocounties.html Colorado County Evolution by Don Stanwyck]
*[http://www.coloradohistory.org/ Colorado Historical Society]
*[https://web.archive.org/web/20081201075235/http://www.co.jefferson.co.us/openspace/openspace_T56_R108.htm Jefferson County Open Space Parks]

{{Geographic Location
|Centre    = Jefferson County, Colorado
|North     = [[Boulder County, Colorado|Boulder County]]
|Northeast = [[Broomfield, Colorado|City and County of Broomfield]]
|East      = [[Adams County, Colorado|Adams County]], [[Denver, Colorado|City and County of Denver]], [[Arapahoe County, Colorado|Arapahoe County]], and [[Douglas County, Colorado|Douglas County]]
|Southeast =
|South     = [[Teller County, Colorado|Teller County]]
|Southwest = [[Park County, Colorado|Park County]]
|West      = [[Clear Creek County, Colorado|Clear Creek County]]
|Northwest = [[Gilpin County, Colorado|Gilpin County]]
}} 
{{Jefferson County, Colorado}}
{{Colorado|show}}
{{authority control}}
{{coord|39.59|-105.25|display=title|type:adm2nd_region:US-CO_source:UScensus1990}}

[[Category:Jefferson County, Colorado| ]]
[[Category:Colorado counties]]
[[Category:1861 establishments in Colorado Territory]]
[[Category:Denver metropolitan area]]
[[Category:Populated places established in 1861]]