Arapahoe County ( ) is a county located in the U.S. state of Colorado. As of the 2020 census, its population was 655,070, making it the third-most populous county in Colorado. The county seat is Littleton, and the most populous city is Aurora. The county was named for the Arapaho Native American tribe, who once lived in the region.
Arapahoe County is part of the Denver-Aurora-Lakewood metropolitan statistical area. Arapahoe County calls itself "Colorado's First County", since its origins antedate the Pike's Peak Gold Rush.
History
On August 25, 1855, the Kansas Territorial Legislature created a huge Arapahoe County to govern the entire western portion of the Territory of Kansas. The county was named for the Arapaho Nation, who 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 a smaller Arapahoe County. Denver City served as the county seat of Arapahoe County.
The Jefferson Territory never received federal sanction, and when the State of Kansas was admitted to the Union on January 29, 1861, the mining regions temporarily reverted to unorganized territory. On February 28, 1861, Congress passed an act organizing the Territory of Colorado, using present-day borders. On November 1, 1861, the Colorado Territorial Assembly organized the 17 original counties of Colorado, including a new Arapahoe County. Arapahoe County originally stretched from the line of present-day Sheridan Boulevard east to the Kansas border, and from the line of present-day County Line Road north to the 40th parallel north (168th Avenue). Denver City served as the county seat of Arapahoe County until 1902.
In 1901, the Colorado General Assembly voted to split Arapahoe County into three parts - a new consolidated City and County of Denver, a new Adams County, and the remainder of the Arapahoe County to be renamed South Arapahoe County. A ruling by the Colorado Supreme Court, subsequent legislation, and a referendum delayed the reorganization until November 15, 1902. Governor James Bradley Orman designated Littleton as the temporary county seat of South Arapahoe County. On April 11, 1903, the Colorado General Assembly changed the name of South Arapahoe County back to Arapahoe County. On November 8, 1904, Arapahoe County voters chose Littleton over Englewood by a vote of 1310 to 829 to be the permanent county seat.
Geography
According to the U.S. Census Bureau, the county has a total area of , of which are land and (0.9%) are covered by water. The county measures east-west and north-south.
Two exclaves of Arapahoe County are entirely surrounded by the City and County of Denver, the City of Glendale, and the Holly Hills neighborhood, a census-designated place.
Adjacent counties
City and County of Denver – northwest and exclaves
Adams County – north
Washington County – east
Lincoln County – southeast
Elbert County – south
Douglas County – southwest
Jefferson County – west
Major highways
Interstate 25
Interstate 70
Interstate 225
U.S. Highway 85
U.S. Highway 285
State Highway 30
State Highway 36
State Highway 40
State Highway 75
State Highway 79
State Highway 83
State Highway 88
State Highway 177
State Highway 470
E-470 (tollway)
State park
Cherry Creek State Park
Historic trails
Smoky Hill Trail
South Platte Trail
Recreation trails
Highline Canal National Recreation Trail
Platte River Greenway National Recreation Trail
Demographics
As of the census of 2000, 487,967 people, 190,909 households, and 125,809 families were residing in the county. The population density was . The 196,835 housing units averaged . The racial makeup of the county was 79.93% White, 7.67% African American, 0.66% Native American, 3.95% Asian, 0.12% Pacific Islander, 4.51% from other races, and 3.16% from two or more races. Hispanics or Latinos of any race made up 11.81% of the population.