Jefferson County, Colorado

Jefferson County, Colorado
Jefferson County, Colorado
Map of Colorado highlighting Jefferson County
Location in the state of Colorado
Map of the U.S. highlighting Colorado
Colorado's location in the U.S.
Founded November 1, 1861
Named for U.S. President Thomas Jefferson
Seat Golden
Largest city Lakewood
 - Total
 - Land
 - Water

778.06 sq mi (2,015 km²)
772.09 sq mi (2,000 km²)
5.97 sq mi (15 km²), 0.77%
 - (2010)
 - Density

683/sq mi (264/km²)
Fourth most populous Colorado county

Jefferson County (play /ˈɛfərsən/), whose slogan is the "Gateway to the Rocky Mountains", is the fourth most populous of the 64 counties of the State of Colorado of the United States. Located along the Front Range of the Rocky Mountains, Jefferson County is adjacent to the west side of the state capital, Denver. The county population was 534,543 according to the 2010 census.[1] The county seat is Golden and the most populous city is Lakewood. Jefferson County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area. As of 2002, Jefferson County contains the state's center of population.[2]

Jefferson County 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 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 is located in Jefferson County, offering programs in mining and engineering.

Jefferson County is where the Columbine High School massacre of 1999 occurred.



On August 25, 1855, the Kansas Territorial Legislature created Arapahoe County to govern the entire western portion of the territory. The county was named for the Arapaho Nation of Native Americans that lived in the region.

In July 1858, gold was discovered along the South Platte River in Arapahoe County (in present day Englewood). This discovery precipitated the Pike's Peak Gold Rush. Many residents of the mining region felt disconnected from the remote territorial governments of Kansas and Nebraska, so they voted to form their own Territory of Jefferson 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, the principal author of the Declaration of Independence and the nation's third president. Golden City served 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 and later at Apex.

The Jefferson Territory never received federal sanction, but during his last week in office, President James Buchanan signed an act which organized the Territory of Colorado on February 28, 1861.[3] That November 1, the new Colorado General Assembly 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 54 miles (87 km). Several annexations by the City & County of Denver and the 2001 consolidation of the City & County of Broomfield removed eastern portions of the county.


The dimensions of the county are 54 miles (87 km) north to south and between 4–18 miles (6.4–29 km) west to east. According to the 2000 census, the county has a total area of 778.06 square miles (2,015.2 km2), of which 772.09 square miles (1,999.7 km2) (or 99.23%) is land and 5.97 square miles (15.5 km2) (or 0.77%) is water.[4]

Adjacent counties

Jefferson County borders ten adjacent counties, the most of any Colorado county:

Recreational areas

  • Alderfer/Three Sisters Park
  • Apex Park
  • Centennial Cone Park
  • Clear Creek Canyon Park
  • Coal Creek Canyon
  • Crown Hill Park
  • Deer Creek Canyon Park
  • Elk Meadow Park
  • 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
  • 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


Historical populations
Census Pop.
1870 2,390
1880 6,804 184.7%
1890 8,450 24.2%
1900 9,306 10.1%
1910 14,231 52.9%
1920 14,400 1.2%
1930 21,810 51.5%
1940 30,725 40.9%
1950 55,687 81.2%
1960 127,520 129.0%
1970 233,031 82.7%
1980 371,753 59.5%
1990 438,430 17.9%
2000 527,056 20.2%
2010 534,543 1.4%
U.S. Decennial Census

As of the census[5] of 2000, there were 527,056 people, 206,067 households, and 140,537 families residing in the county. The population density was 683 people per square mile (264/km²). There were 212,488 housing units at an average density of 275 per square mile (106/km²). The racial makeup of the county was 90.59% White, 0.89% Black or African American, 0.75% Native American, 2.28% Asian, 0.08% Pacific Islander, 3.23% from other races, and 2.18% from two or more races. 9.95% of the population were Hispanic or Latino of any race.

There were 206,067 households out of which 33.40% had children under the age of 18 living with them, 55.10% were 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 and 6.30% had 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.

In the county the population was spread out with 25.30% under the age of 18, 8.10% from 18 to 24, 32.10% from 25 to 44, 24.90% from 45 to 64, and 9.60% who were 65 years of age or older. The median age was 37 years. 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 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 65 or over.





Unincorporated Census Designated Places


Jefferson County School District R-1.

Government and infrastructure

The Federal Correctional Institution, Englewood is in unincorporated Jefferson County.[6]

State parks

National forests and wilderness

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

See also


External links

Coordinates: 39°35′N 105°15′W / 39.59°N 105.25°W / 39.59; -105.25

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Look at other dictionaries:

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  • Jefferson County — is the name of 25 counties and one parish in the United States: Jefferson County, Alabama Jefferson County, Arkansas Jefferson County, Colorado Jefferson County, Florida Jefferson County, Georgia Jefferson County, Idaho Jefferson County, Illinois …   Wikipedia

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  • Jefferson County (Jefferson-Territorium) — Der Jefferson County war ein County des außerhalb des US Gesetzes liegenden Jefferson Territoriums, das vom 28. November 1859 bis zum 28. Februar 1861 bestand. Inhaltsverzeichnis 1 Geschichte 2 County Territorium 3 Kreisstadt …   Deutsch Wikipedia

  • Jefferson County, Jefferson Territory — The original Jefferson County in what is now the State of Colorado was organized in 1859 by the extra legal provisional government of the Territory of Jefferson. Its territory covered a broad swath surrounding the region of the Pike s Peak Gold… …   Wikipedia

  • Jefferson County — Es gibt in den Vereinigten Staaten 26 Countys oder Parishes mit dem Namen Jefferson: Jefferson County (Alabama) Jefferson County (Arkansas) Jefferson County (Colorado) Jefferson County (Florida) Jefferson County (Georgia) Jefferson County (Idaho) …   Deutsch Wikipedia

  • Jefferson County (Texas) — Jefferson County Courthouse Verwaltung US Bundesstaat: Texas V …   Deutsch Wikipedia

  • Jefferson County Airport — may refer to:* Jefferson County International Airport in Jefferson County, Washington, United States (FAA: 0S9). * Jefferson County Airpark in Jefferson County, Ohio, United States (FAA: 2G2). * DuBois Regional Airport, formerly DuBois Jefferson… …   Wikipedia

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