The U.S. State of Colorado is divided into 64 counties. Two of these, the City and County of Denver, which serves as the state capital, and the City and County of Broomfield, have consolidated city and county governments. In addition to Denver and Broomfield, Pitkin County and Weld County operate as home rule counties with their own county charters. The other 60 counties operate under state regulations per Dillon's Rule. Counties are important units of government in Colorado since there are no civil townships or other minor civil divisions.
The United States Census Bureau estimates that El Paso County remains the most populous county in Colorado with a population estimate of 752,772, as of July 1, 2024, while Hinsdale County with a population of 747 is now the least populous. Five of the 64 Colorado counties now have more than 500,000 residents, while 12 counties have fewer than 5,000 residents.
Las Animas County, in area, is the most extensive county, while the City and County of Broomfield, in area, is the least extensive. The City and County of Denver is the most densely populated Colorado county, with a 2024 population density of 4,918 residents per square mile of land area (1,899/km<sup>2</sup>), while Hinsdale County is the least densely populated county, with a 2024 population density of 0.67 resident per square mile of land area (0.26/km<sup>2</sup>).
Mount Elbert, the highest summit of Colorado and the entire Rocky Mountains at an elevation of , is located in Lake County. The lowest point in Colorado is where the Arikaree River flows out of Yuma County and into Kansas, at elevation. This point, which is the highest low point of any state, is higher than the highest points of 18 states and the District of Columbia.
On November 1, 1861, the new Territory of Colorado created 17 original counties: Arapahoe, Boulder, Clear Creek, Costilla, Douglas, El Paso, Fremont, Gilpin, Guadalupe, Huerfano, Jefferson, Lake, Larimer, Park, Pueblo, Summit, and Weld; plus the Cheyenne Reserve. Six days later, the name of Guadelupe County was changed to Conejos County.
On February 9, 1866, the first new county, Las Animas, was created, followed by Saguache in December of that year. Bent County was created in February 1870, followed by Greenwood the following month. On February 2, 1874, Grand County and Elbert County were formed, and on February 10, La Plata, Hinsdale, and Rio Grande counties were created. Greenwood was absorbed into Bent on February 5. The last county to be created under the Colorado Territory name was San Juan County, created three months before statehood.
By the time Colorado became a state on August 1, 1876, it had only 26 counties. In January 1877, Routt and Ouray were formed, followed by Gunnison and Custer counties in March. In February 1879, Chaffee County was created. From February 8âÂÂ10, 1879, Lake county was renamed Carbonate County. In 1881, Dolores County and Pitkin County were created. In 1883, Montrose, Mesa, Garfield, Eagle, Delta, and San Miguel counties were formed, leaving the total number of counties at 39. The number rose to 40 in 1885 with the creation of Archuleta County on April 14. Washington County and Logan County were both created in 1887. Between February 19 and April 16 in 1889, Morgan, Yuma, Cheyenne, Otero, Rio Blanco, Phillips, Sedgwick, Kiowa, Kit Carson, Lincoln, Prowers, Baca, and Montezuma counties were formed, bringing the total to 55. By 1900, Mineral County and Teller County had been added. On November 15, 1902, Arapahoe County was split into Adams and South Arapahoe Counties, and Denver was reconstituted as a consolidated city-county from portions of both newly formed counties on December 1, 1902. By 1912, Jackson County, Moffat County, and Crowley County had been created. Alamosa was created in 1913. In 2001, Broomfield was reconstituted as a consolidated city-county from parts of Adams, Boulder, Jefferson and Weld counties, bringing the total to 64 counties.
Select the OpenStreetMap link at the right to view the location of these 64 counties.
The following lists all the historic counties of the Territory of New Mexico, the Territory of Utah, the Territory of Kansas, and the extralegal Territory of Jefferson that previously existed within the boundaries of the present State of Colorado, as well as the three defunct counties of the Territory of Colorado and the three defunct counties of the State of Colorado.
Of the 64 Colorado counties, 20 counties extend above elevation, 32 counties extend above , 42 counties extend above , and all 64 Colorado counties extend above .
Of Colorado's 64 counties, 4 counties have a mean elevation above elevation, 22 counties have a mean elevation above , 32 counties have a mean elevation above , and all 64 counties have a mean elevation above .
The following 13 Colorado counties have highest mean elevation of any county in the United States, exceeding even the Denali Borough of Alaska.