Jefferson County is a

county A county is a geographic region of a country used for administrative or other purposes Chambers Dictionary, L. Brookes (ed.), 2005, Chambers Harrap Publishers Ltd, Edinburgh in certain modern nations. The term is derived from the Old French ...

located in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...

. As of the 2020 census, the population was 582,910, making it the fourth-most populous county in Colorado. The

county seat A county seat is an administrative center, seat of government, or capital city of a county or civil parish. The term is in use in Canada, China, Hungary, Romania, Taiwan, and the United States. The equivalent term shire town is used in the US ...

is Golden, and the most populous city is Lakewood. Jefferson County is included in the

Denver Denver () is a consolidated city and county, the capital, and most populous city of the U.S. state of Colorado. Its population was 715,522 at the 2020 census, a 19.22% increase since 2010. It is the 19th-most populous city in the Unit ...

Aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...

-Lakewood, CO

Metropolitan Statistical Area In the United States, a metropolitan statistical area (MSA) is a geographical region with a relatively high population density at its core and close economic ties throughout the area. Such regions are neither legally incorporated as a city or tow ...

. Located along the

Front Range The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the central portion of the U.S. State of Colorado, and southeastern portion of the U.S. State of Wyoming. It is the first mountain range encountered ...

of the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

, Jefferson County is adjacent to the state capital of Denver. In 2010, the center of population of Colorado was located in Jefferson County. The county's slogan is the "Gateway to the Rocky Mountains", and it is commonly nicknamed 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 Rocky Mountain Metropolitan Airport is a public-use airport located in Broomfield, Colorado, United States. The airport is owned and operated by Jefferson County and is situated midway between Denver and Boulder on U.S. Highway 36. It is loc ...

operated by Jefferson County was previously known as the Jeffco Airport. A major employer in Jefferson County is the large

Coors Brewing Company The Coors Brewing Company started as an American brewery and beer company in Golden, Colorado. In 2005, Adolph Coors Company, the holding company that owned Coors Brewing, merged with Molson, Inc. to become Molson Coors. The first Coors b ...

in Golden. Also, the state-supported

Colorado School of Mines The Colorado School of Mines, informally called Mines, is a public research university in Golden, Colorado, founded in 1874. The school offers both undergraduate and graduate degrees in engineering, science, and mathematics, with a focus on en ...

, a university specializing in

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...

geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

, and

engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more speciali ...

is located in Jefferson County.

History

On August 25, 1855, the

Kansas Territorial Legislature The Kansas Legislature is the state legislature of the U.S. state of Kansas. It is a bicameral assembly, composed of the lower Kansas House of Representatives, with 125 state representatives, and the upper Kansas Senate, with 40 state senators ...

created

Arapahoe County Arapahoe County may refer to: *Arapahoe County, Colorado *Arapahoe County, Kansas Territory Arapahoe County was a county of Kansas Territory in the United States that existed from August 25, 1855, until Kansas's admission into the Union on January ...

to govern the entire western portion of the

territory A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...

. The county was named for the Arapaho Nation of Native Americans who lived in the region. On June 22, 1858,

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

was discovered along the

South Platte River The South Platte River is one of the two principal tributaries of the Platte River. Flowing through the U.S. states of Colorado and Nebraska, it is itself a major river of the American Midwest and the American Southwest/Mountain West. It ...

(in present-day Englewood). This discovery precipitated the

Pike's Peak Gold Rush The Pike's Peak Gold Rush (later known as the Colorado Gold Rush) was the boom in gold prospecting and mining in the Pike's Peak Country of western Kansas Territory and southwestern Nebraska Territory of the United States that began in July 1858 ...

. Many residents of the mining region felt disconnected from the remote territorial governments of

Kansas Kansas () is a U.S. state, state in the Midwestern United States, Midwestern United States. Its Capital city, capital is Topeka, Kansas, Topeka, and its largest city is Wichita, Kansas, Wichita. Kansas is a landlocked state bordered by Nebras ...

and

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...

, so they voted to form their own

Territory of Jefferson The Territory of Jefferson was an extralegal and unrecognized United States territory that existed from October 24, 1859 until the creation of the Colorado Territory on February 28, 1861. The Jefferson Territory, named for Founding Father and Un ...

on October 24, 1859. The following month, the Jefferson Territorial Legislature organized 12 counties for the new territory, including Jefferson County. Jefferson County was named for the namesake of the Jefferson Territory,

Thomas Jefferson Thomas Jefferson (April 13, 1743 – July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Fathers of the United States, Founding Father who served as the third president of the United States from 18 ...

, the principal author of the

Declaration of Independence A declaration of independence or declaration of statehood or proclamation of independence is an assertion by a polity in a defined territory that it is independent and constitutes a state. Such places are usually declared from part or all of th ...

and the nation's third

president President most commonly refers to: *President (corporate title) * President (education), a leader of a college or university * President (government title) President may also refer to: Automobiles * Nissan President, a 1966–2010 Japanese ...

. Golden City served as the

of Jefferson County.

Robert Williamson Steele Robert Williamson Steele (January 14, 1820 – February 7, 1901) was governor of the extralegal Territory of Jefferson, which existed in the western United States from 1859 to 1861, when it was replaced by the Territory of Colorado. Early l ...

Governor A governor is an administrative leader and head of a polity or political region, ranking under the head of state and in some cases, such as governors-general, as the head of state's official representative. Depending on the type of political ...

of the

Provisional Government of the Territory of Jefferson The Territory of Jefferson was an extralegal and unrecognized United States territory that existed from October 24, 1859 until the creation of the Colorado Territory on February 28, 1861. The Jefferson Territory, named for Founding Father and U ...

from 1859 to 1861, built his home in the county at

Mount Vernon Mount Vernon is an American landmark and former plantation of Founding Father, commander of the Continental Army in the Revolutionary War, and the first president of the United States George Washington and his wife, Martha. The estate is on ...

and later at

Apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

. The Jefferson Territory never received federal sanction, but during his last week in office,

President President most commonly refers to: *President (corporate title) * President (education), a leader of a college or university * President (government title) President may also refer to: Automobiles * Nissan President, a 1966–2010 Japanese ...

James Buchanan James Buchanan Jr. ( ; April 23, 1791June 1, 1868) was an American lawyer, diplomat and politician who served as the 15th president of the United States from 1857 to 1861. He previously served as secretary of state from 1845 to 1849 and repr ...

signed an act which organized the

Territory of Colorado The Territory of Colorado was an organized incorporated territory of the United States that existed from February 28, 1861, until August 1, 1876, when it was admitted to the Union as the State of Colorado. The territory was organized in the ...

on February 28, 1861. That November 1, the new

Colorado General Assembly The Colorado General Assembly is the state legislature of the State of Colorado. It is a bicameral legislature that was created by the 1876 state constitution. Its statutes are codified in the ''Colorado Revised Statutes'' (C.R.S.). The se ...

organized the 17 original counties of Colorado, including a new Jefferson County. In 1908, the southern tip of Jefferson County was transferred to Park County, reducing Jefferson County to its present length of . Several annexations by the City & County of Denver and the 2001 consolidation of the City & County of Broomfield removed the east and extreme northeastern corner of the county, respectively.

Geography

According to the

U.S. Census Bureau The United States Census Bureau (USCB), officially the Bureau of the Census, is a principal agency of the U.S. Federal Statistical System, responsible for producing data about the American people and economy. The Census Bureau is part of the ...

, the county has a total area of , of which is land and (1.3%) is water.

Adjacent counties

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

Boulder County Boulder County is a county located in the U.S. state of Colorado of the United States. As of the 2020 census, the population was 330,758. The most populous municipality in the county and the county seat is Boulder. Boulder County comprises th ...

– north * City and County of Broomfield – northeast * Adams County – east * City and County of Denver – east *

– east * Douglas County – east * Teller County – south * Park County – southwest *

Clear Creek County Clear Creek County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 9,397. The county seat is Georgetown. Clear Creek County is part of the Denver metropolitan area. History Clear Creek County ...

– west *

Gilpin County Gilpin County is a county located in the U.S. state of Colorado, smallest in land area behind only the City and County of Broomfield. As of the 2020 census, the population was 5,808. The county seat is Central City. The county was formed in 18 ...

– northwest

Major highways

Interstate 70 Interstate 70 (I-70) is a major east–west Interstate Highway in the United States that runs from I-15 near Cove Fort, Utah, to a park and ride lot just east of I-695 in Baltimore, Maryland, and is the fifth-longest Interstate in the co ...

* *

U.S. Highway 6 * US 40

U.S. Highway 40 * US 285

U.S. Highway 285 * Colorado 8

State Highway 8 * Colorado 58

State Highway 58 * Colorado 72

State Highway 72 * Colorado 74

State Highway 74 * Colorado 75

State Highway 75 * Colorado 93

State Highway 93 * Colorado 121

State Highway 121 * Colorado 391

State Highway 391 * Colorado 470

State Highway 470 * Chatfield Ave * 44th Ave

Recreational areas

*Alderfer/Three Sisters Park *Apex Park *Bear Creek Lake Park *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

Demographics

As of the

census A census is the procedure of systematically acquiring, recording and calculating information about the members of a given population. This term is used mostly in connection with national population and housing censuses; other common censuses inc ...

of 2000, there were 527,056 people, 206,067 households, and 140,537 families residing in the county. The

population density Population density (in agriculture: standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geographical term.Matt RosenberPopu ...

was 683 people per square mile (264 people/km). There were 212,488 housing units at an average density of 275 people per square mile (106 people/km). The racial makeup of the county was : There were 206,067 households, out of which 33.40% had children under age 18 living with them, 55.10% were

married couples Marriage, also called matrimony or wedlock, is a culturally and often legally recognized union between people called spouses. It establishes rights and obligations between them, as well as between them and their children, and between ...

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 years of age or older. The average household size was 2.52, and the average family size was 3.03 persons. In the county, the population ages were spread out: : For every 100 females there were 99.00 males. For every 100 females age 18 and over, there were 96.80 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 Per capita income (PCI) or total income measures the average income earned per person in a given area (city, region, country, etc.) in a specified year. It is calculated by dividing the area's total income by its total population. Per capita i ...

for the county was $28,066. About 3.40% of families and 5.20% of the population were below the

poverty line The poverty threshold, poverty limit, poverty line or breadline is the minimum level of income deemed adequate in a particular country. The poverty line is usually calculated by estimating the total cost of one year's worth of necessities for ...

, including 5.80% of those under age 18, and 5.10% of those age 65 or over. According to a report in the

JAMA ''The Journal of the American Medical Association'' (''JAMA'') is a peer-reviewed medical journal published 48 times a year by the American Medical Association. It publishes original research, reviews, and editorials covering all aspects of biom ...

, residents of Jefferson County had a 2014 life expectancy of 80.02 years.

Education

The sole school district serving the county is

Jefferson County School District R-1 Jefferson County School District R-1 (a.k.a. Jefferson County Public Schools or Jeffco Public Schools) is a school district in Jefferson County, Colorado. The district is headquartered at the Jeffco Public Schools Education Center in West Pleasant ...

. ;Private schools: *

Colorado Academy Colorado Academy is an independent nonsectarian, co-educational, college preparatory day school for students from Pre-Kindergarten through Twelfth Grade. The school's campus is located in Lakewood, Colorado, and serves approximately 1000 studen ...

;Tertiary institutions: *

Colorado Christian University Colorado Christian University (CCU) is a private Christian university in Lakewood, Colorado. CCU was founded by Clifton Fowler in 1914 as the Denver Bible Institute. History CCU's heritage dates back to the formation of Denver Bible Institute in ...

Colorado School of Trades The Colorado School of Trades is a private for-profit school in Lakewood, Colorado that focuses exclusively on gunsmithing A gunsmith is a person who repairs, modifies, designs, or builds guns. The occupation differs from an armorer, who usuall ...

Jefferson County Public Library is the county library system.

Government and infrastructure

*The

Federal Correctional Institution, Englewood The Federal Correctional Institution, Englewood (FCI Englewood) is a low-security United States federal prison for male inmates in Colorado. It is operated by the Federal Bureau of Prisons (BOP), a division of the United States Department of Jus ...

is in

unincorporated Unincorporated may refer to: * Unincorporated area, land not governed by a local municipality * Unincorporated entity, a type of organization * Unincorporated territories of the United States, territories under U.S. jurisdiction, to which Congress ...

Jefferson County. *The

Rocky Flats Plant The Rocky Flats Plant was a U.S. manufacturing complex that produced nuclear weapons parts in the western United States, near Denver, Colorado. The facility's primary mission was the fabrication of plutonium pits, which were shipped to ...

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 "Taj Mahal". *The

Denver Federal Center The Denver Federal Center, in Lakewood, Colorado, is part of the General Services Administration and is home to about 6,200 employees of agencies of the federal government of the United States. The Center encompasses an area of about and has 9 ...

, the largest concentration of federal government agencies outside of Washington, D.C., is located in Lakewood.

Sheriff's office

The Jefferson County Sheriff's Office responded to the 1999

Columbine High School massacre On April 20, 1999, a school shooting and attempted bombing occurred at Columbine High School in Columbine, Colorado, United States. The perpetrators, 12th grade students Eric Harris and Dylan Klebold, murdered 12 students and one teacher. ...

, 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 Eric David Harris (April 9, 1981 – April 20, 1999) and Dylan Bennet Klebold (; September 11, 1981 – April 20, 1999) were an American mass murder duo who perpetrated the Columbine High School massacre on April 20, 1999. Harris and Klebol ...

in and out of custody prior to the shooting. After the shooting

Sue Klebold Susan Francis Klebold (''née'' Yassenoff; born March 25, 1949) is an American author and activist. She is the mother of Dylan Klebold, one of the perpetrators of the Columbine High School massacre that occurred on April 20, 1999. She is the au ...

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. This lawsuit was dismissed along with several others pertaining to the shooting.

Politics

Jefferson County was a Republican stronghold for most of the 20th century. However, it has voted Democratic in every presidential election since 2008, consistent with the general trend in the Denver metropolitan area. In 2020, Joe Biden won the largest percentage for a Democratic presidential candidate since 1916.

Recreation

State parks

Chatfield State Park Chatfield State Park is a state park located in Douglas and Jefferson counties of Colorado, United States. The park centers on Chatfield Reservoir, a 1,423 acre surface area lake fed by the South Platte River and two other creeks, including ...

Golden Gate Canyon State Park Golden Gate Canyon State Park is a Colorado State Park located in Gilpin and Jefferson counties northwest of Golden, Colorado. The Front Range park established in 1960 has of hiking trails. Horse and bicycle travel is allowed on . Facil ...

Staunton State Park Staunton State Park is a Colorado state park in Park and Jefferson counties, located west of Conifer, Colorado. The park, which opened on May 18, 2013, includes dramatic rock outcroppings, several streams and a waterfall. On December 4, 20 ...

National forests and wilderness

* Pike National Forest *

Roosevelt National Forest The Roosevelt National Forest is a National Forest located in north central Colorado. It is contiguous with the Colorado State Forest as well as the Arapaho National Forest and the Routt National Forest. The forest is administered jointly with ...

Lost Creek Wilderness The Lost Creek Wilderness is a wilderness area located in central Colorado in Jefferson and Park counties, south of the town of Bailey. The area is situated entirely within the boundaries of the Pike National Forest. The Lost Creek Scenic Are ...

National wildlife refuges

Rocky Flats National Wildlife Refuge The Rocky Flats National Wildlife Refuge is National Wildlife Refuge in the United States, located approximately northwest of Denver, Colorado. The refuge is situated west of the cities of Broomfield and Westminster and situated north of the ...

* Two Ponds National Wildlife Refuge

Historic trail

South Platte Trail South Platte Trail was a historic trail that followed the southern side of South Platte River from Fort Kearny in Nebraska to Denver, Colorado. Plains Indians, such as the Cheyenne and the Arapaho, hunted in the lands around the South Platte Riv ...

Recreational trails

American Discovery Trail The American Discovery Trail is a system of recreational trails and roads that collectively form a coast-to-coast hiking and biking trail across the mid-tier of the United States. Horses can also be ridden on most of this trail. The coastal tra ...

* Apex National Recreation Trail * Big Dry Creek National Recreation Trail *

Colorado Trail The Colorado Trail is a long-distance trail running for from the mouth of Waterton Canyon southwest of Denver to Durango in Colorado, United States. Its highest point is above sea level, and most of the trail is above . Despite its high elevat ...

Platte River Greenway National Recreation Trail Platte may refer to: Geography United States * Platte, Minnesota, an unincorporated community * Platte, South Dakota, a city * Platte Canyon, Colorado * Platte City, Missouri * Platte Lake (disambiguation), also Lake Platte * Platte River (disa ...

* Two Ponds National Recreation Trail

Scenic byway

* Lariat Loop Scenic and Historic Byway

Golf course

* Hiwan Golf Club * Indian Tree Golf Club

Communities

Cities

Arvada Arvada () is a home rule municipality located in Jefferson and Adams counties, Colorado, United States. The city population was 124,402 at the 2020 United States Census, with 121,510 residing in Jefferson County and 2,892 residing in Adams Cou ...

(part) * Edgewater * Golden * Lakewood * Littleton (part) *

Westminster Westminster is an area of Central London, part of the wider City of Westminster. The area, which extends from the River Thames to Oxford Street, has many visitor attractions and historic landmarks, including the Palace of Westminster, B ...

(part) *

Wheat Ridge The City of Wheat Ridge is a home rule municipality located in Jefferson County, Colorado, United States. Wheat Ridge is located immediately west of Denver and is a part of the Denver–Aurora–Lakewood, CO Metropolitan Statistical Area. The ...

Towns

* Bow Mar (part) * Lakeside * Morrison * Mountain View *

Superior Superior may refer to: *Superior (hierarchy), something which is higher in a hierarchical structure of any kind Places *Superior (proposed U.S. state), an unsuccessful proposal for the Upper Peninsula of Michigan to form a separate state *Lake ...

(part)

Census-designated places

* Applewood * Aspen Park * Brook Forest * Coal Creek (part) * Columbine * Dakota Ridge * East Pleasant View *

Evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

* Fairmount *

Genesee Genesee, derived from the Seneca word for "pleasant valley", may refer to: Geographic features Canada *Genesee, Alberta, an unincorporated community United States *Genesee, California *Genesee, Colorado *Genesee County, Michigan *Genesee Co ...

* Idledale * Indian Hills * Ken Caryl * Kittredge * West Pleasant View

Unincorporated communities

* Buffalo Creek *

Conifer Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...

* Foxton *

Pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...

* Pine Junction *

Plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adapta ...

References

External links

Jefferson County Government websiteColorado Historical Society
{{Authority control Colorado counties 1861 establishments in Colorado Territory Denver metropolitan area Populated places established in 1861