List of counties in Colorado

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, while Hinsdale County is the least densely populated county, with a 2024 population density of 0.67 resident per square mile of land area.
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.

History

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 8–10, 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.

Colorado counties

Select the OpenStreetMap link at the right to view the location of these 64 counties.

County population

Former counties

The following sortable table 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.

County	Territory or State	Date created	Date superseded	History
Taos County	Territory of New Mexico	Jan 09, 1852	Feb 28, 1861	Originally one of the seven partidos of the Spanish, and later Mexican, province of Santa Fe de Nuevo México. One of the nine original counties created by the Territory of New Mexico in 1852. Excluded from the new Territory of Colorado in 1861.
Great Salt Lake County	Territory of Utah	Mar 03, 1852	Feb 28, 1861	Created in 1852. Excluded from the new Territory of Colorado in 1861.
Green River County	Territory of Utah	Mar 03, 1852	Feb 28, 1861	Created in 1852, but never organized. Dissolved in 1857, but recreated in 1859. Excluded from the new Territory of Colorado in 1861, and the Territory of Wyoming in 1868. Finally dissolved in 1872.
Iron County	Territory of Utah	Mar 03, 1852	Feb 28, 1861	Created in 1852. Excluded from the new Territory of Colorado in 1861.
Sanpete County	Territory of Utah	Mar 03, 1852	Feb 28, 1861	Created in 1852. Excluded from the new Territory of Colorado in 1861.
Utah County	Territory of Utah	Mar 03, 1852	Feb 28, 1861	Created in 1852. Excluded from the new Territory of Colorado in 1861.
Washington County	Territory of Utah	Mar 03, 1852	Feb 28, 1861	Created in 1852. Excluded from the new Territory of Colorado in 1861.
Arapahoe County	Territory of Kansas	Aug 25, 1855	Feb 28, 1861	Created in 1855, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
Beaver County	Territory of Utah	Jan 05, 1856	Feb 28, 1861	Split from Iron and Millard counties in 1856. Excluded from the new Territory of Colorado in 1861.
Broderick County	Territory of Kansas	Feb 07, 1859	Jan 29, 1861	Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
El Paso County	Territory of Kansas	Feb 07, 1859	Jan 29, 1861	Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
Fremont County	Territory of Kansas	Feb 07, 1859	Jan 29, 1861	Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
Montana County	Territory of Kansas	Feb 07, 1859	Jan 29, 1861	Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
Oro County	Territory of Kansas	Feb 07, 1859	Jan 29, 1861	Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
Peketon County	Territory of Kansas	Feb 07, 1859	Jan 29, 1861	Created in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.
Arrappahoe County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Cheyenne County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
El Paso County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Fountain County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Heele County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Jackson County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Jefferson County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Mountain County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
North County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Park County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
St. Vrain's County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Saratoga County	Territory of Jefferson	Nov 28, 1859	Feb 28, 1861	One of the 12 counties created by the extralegal Territory of Jefferson in 1859.
Mora County	Territory of New Mexico	Feb 01, 1860	Feb 28, 1861	Split from Taos County and San Miguel County in 1860. Excluded from the new Territory of Colorado in 1861.
Guadalupe County	Territory of Colorado	Nov 01, 1861	Nov 07, 1861	One of the 17 original counties created by the Territory of Colorado in 1861. The county was renamed Conejos County after only six days.
Greenwood County	Territory of Colorado	Feb 11, 1870	Feb 02, 1874	Created from expropriated Cheyenne and Arapaho tribal land and the eastern portion of Huerfano County in 1870. The county was abolished in 1874 and its territory split between Elbert County and Bent County.
Platte County	Territory of Colorado	Feb 09, 1872	Feb 09, 1874	Created from the eastern portion of Weld County in 1872. The county was abolished in 1874 after organizers failed to secure voter approval. The territory of the county was returned to Weld County.
Carbonate County	State of Colorado	Feb 08, 1879	Feb 10, 1879	Lake County was renamed Carbonate County in 1879. Only two days later, Carbonate County was split into the new Chaffee County and a recreated Lake County.
Uncompahgre County	State of Colorado	Feb 27, 1883	Mar 02, 1883	Ouray County was renamed Uncompahgre County for only four days in 1883.
South Arapahoe County	State of Colorado	Nov 15, 1902	Apr 11, 1903	One of three counties created from Arapahoe County in 1902. The name was changed back to Arapahoe County after five months.