List of counties in Colorado

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.^[3][4] 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.^[5] 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.

County	FIPS code[6][b]	County seat[7][8]	Est.[9]	Formed from[9]	Etymology[9]	Population[10]	Area[7]	Map
Adams County	001	Brighton	1902-11-15	Split from Arapahoe County.	Named in honor of Alva Adams, the 5th, 10th, and 14th Governor of the State of Colorado.	533,365	1,182.29 sq mi (3,062 km2)
Alamosa County	003	Alamosa	1913-03-08	Split from Costilla County and Conejos County.	Named for the cottonwood trees which grow along the Rio Grande and its tributaries. Alamosa is a Spanish word for a cottonwood grove.	16,655	723.21 sq mi (1,873 km2)
Arapahoe County	005	Littleton	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado. Renamed South Arapahoe County for the five months from November 15, 1902 to April 11, 1903.	Named for predecessor Arapahoe County, Kansas Territory, which in turn was named for the Arapaho Nation of Native Americans.	656,061	804.41 sq mi (2,083 km2)
Archuleta County	007	Pagosa Springs	1885-04-14	Split from Conejos County.	Named in honor of Colorado State Senator Antonio D. Archuleta and his father, José Manuel Archuleta.	14,189	1,354.53 sq mi (3,508 km2)
Baca County	009	Springfield	1889-04-16	Split from Las Animas County.	Named in honor of pioneer and Colorado territorial legislator Felipe Baca.	3,344	2,558.48 sq mi (6,626 km2)
Bent County	011	Las Animas	1870-02-11	Split from Huerfano County and former Cheyenne and Arapaho tribal land.	Named in honor of frontier trader William Bent.	5,681	1,541.07 sq mi (3,991 km2)
Boulder County	013	Boulder	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for the abundance of granite boulders along Boulder Creek.	326,831	740.48 sq mi (1,918 km2)
City and County of Broomfield	014	Broomfield	2001-11-15	Split from Boulder, Adams, Jefferson, and Weld counties and reorganized as a consolidated city and county.	Named for the broom corn that was formerly grown in the area.	76,860	33.57 sq mi (87 km2)
Chaffee County	015	Salida	1879-02-10	Split from Carbonate County.	Named in honor of Jerome Bunty Chaffee, one of Colorado's first two U.S. Senators from 1876 to 1879.	20,617	1,014.12 sq mi (2,627 km2)
Cheyenne County	017	Cheyenne Wells	1889-03-25	Split from Elbert and Bent counties.	Named for the Cheyenne Nation of Native Americans.	1,727	1,781.90 sq mi (4,615 km2)
Clear Creek County	019	Georgetown	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for Clear Creek which originates in the county.	9,147	396.53 sq mi (1,027 km2)
Conejos County	021	Conejos	1861-11-01	Guadalupe County, one of the 17 original counties of the Territory of Colorado, was renamed Conejos County after six days on November 7, 1861.	Named for the cottontail rabbits in the area. Conejos is a Spanish word for rabbits.	7,521	1,290.22 sq mi (3,342 km2)
Costilla County	023	San Luis	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for the Costilla River. Costilla is a Spanish word meaning either little rib or furring timber.	3,628	1,229.38 sq mi (3,184 km2)
Crowley County	025	Ordway	1911-05-29	Split from Otero County.	Named in honor of Colorado State Senator John H. Crowley.	5,636	800.27 sq mi (2,073 km2)
Custer County	027	Westcliffe	1877-03-09	Split from Fremont County.	Named in memory of George Armstrong Custer, (1839–1876), the U.S. Army colonel defeated and killed at the Battle of the Little Bighorn.	5,534	739.24 sq mi (1,915 km2)
Delta County	029	Delta	1883-02-11	Split from Gunnison County.	Named for the town of Delta located at the delta of the Uncompahgre River.	31,746	1,149.44 sq mi (2,977 km2)
City and County of Denver	031	Denver	1902-12-01	The original Arapahoe County Seat was split from Arapahoe and the newly-created Adams Counties, and reorganized as a consolidated city and county.	Named to curry favor with James W. Denver, Governor of the Territory of Kansas from 1857 to 1859.	716,577	155.66 sq mi (403 km2)
Dolores County	033	Dove Creek	1881-03-04	Split from Ouray County.	Named for the Dolores River, which was originally named el Rio de Nuestra Senora de los Dolores, which is Spanish for the River of our Lady of Sorrows.	2,513	1,076.93 sq mi (2,789 km2)
Douglas County	035	Castle Rock	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named in honor of Stephen Arnold Douglas, (1813–1861), U.S. Senator from Illinois from 1847 to 1861.	383,906	842.30 sq mi (2,182 km2)
Eagle County	037	Eagle	1883-02-11	Split from Summit County.	Named for the Eagle River which originates in the county.	54,381	1,700.76 sq mi (4,405 km2)
El Paso County	041	Colorado Springs	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for Ute Pass, which connects the Great Plains to South Park and was formerly located within the county. El Paso means the pass in Spanish.	744,215	2,128.60 sq mi (5,513 km2)
Elbert County	039	Kiowa	1874-02-02	Split from Douglas County.	Named in honor of Samuel Hitt Elbert, the sixth Governor of the Territory of Colorado.	28,806	1,849.08 sq mi (4,789 km2)
Fremont County	043	Cañon City	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named in honor of John Charles Frémont (1813–1890), the explorer, U.S. Army general, and U.S. Senator from California.	50,318	1,533.09 sq mi (3,971 km2)
Garfield County	045	Glenwood Springs	1883-02-10	Split from Summit County.	Named in honor of James Abram Garfield (1831–1881), the twentieth President of the United States.	62,707	2,958.23 sq mi (7,662 km2)
Gilpin County	047	Central City	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named in honor of William Gilpin, the first Governor of the Territory of Colorado.	5,926	150.15 sq mi (389 km2)
Grand County	049	Hot Sulphur Springs	1874-02-02	Split from Summit County.	Named for the Grand River which originates in the county. The Grand River was renamed the Colorado River in 1921, but the county retains the original name.	15,935	1,868.53 sq mi (4,839 km2)
Gunnison County	051	Gunnison	1877-03-09	Split from Lake County.	Named in honor of John Williams Gunnison, the U.S. Army captain who explored the region.	17,321	3,259.22 sq mi (8,441 km2)
Hinsdale County	053	Lake City	1874-02-10	Split from Lake, Conejos, and Costilla counties.	Named in honor of George Aaron Hinsdale, a Lieutenant Governor of the Territory of Colorado.	788	1,123.35 sq mi (2,909 km2)
Huerfano County	055	Walsenburg	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for Huerfano Butte, a solitary volcanic plug. Huérfano is a Spanish word meaning orphan.	7,055	1,592.37 sq mi (4,124 km2)
Jackson County	057	Walden	1909-05-05	Split from Larimer County.	Named in honor of Andrew Jackson (1767–1845), the seventh President of the United States.	1,309	1,619.75 sq mi (4,195 km2)
Jefferson County	059	Golden	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for its extralegal predecessor county, Jefferson County, Jefferson Territory, which in turn was named in honor of Thomas Jefferson (1743–1826), the author of the Declaration of Independence and the third President of the United States.	576,366	772.85 sq mi (2,002 km2)
Kiowa County	061	Eads	1889-04-11	Split from Bent County.	Named for the Kiowa Nation of Native Americans.	1,384	1,785.90 sq mi (4,625 km2)
Kit Carson County	063	Burlington	1889-04-11	Split from Elbert County.	Named in honor of Christopher Houston "Kit" Carson, the famous frontier scout and soldier.	6,994	2,162.43 sq mi (5,601 km2)
La Plata County	067	Durango	1874-02-10	Split from Lake and Conejos counties.	Named for the many silver deposits in the area. La plata is a Spanish expression for the silver.	56,407	1,700.44 sq mi (4,404 km2)
Lake County	065	Leadville	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado. Renamed Carbonate County for the two days from February 8–10, 1879.	Named for the Twin Lakes in the county.	7,365	383.55 sq mi (993 km2)
Larimer County	069	Fort Collins	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named in honor of William Larimer, a pioneer entrepreneur.	370,771	2,631.75 sq mi (6,816 km2)
Las Animas County	071	Trinidad	1866-02-09	Split from Huerfano County.	Named for the Purgatoire River, which was originally named el Rio de las Animas Perdidas, which is Spanish for the River of the Souls in Purgatory.	14,348	4,773.27 sq mi (12,363 km2)
Lincoln County	073	Hugo	1889-04-11	Split from Elbert and Bent counties.	Named in honor of Abraham Lincoln (1809–1865), the sixteenth President of the United States.	5,480	2,585.21 sq mi (6,696 km2)
Logan County	075	Sterling	1887-02-25	Split from Weld County.	Named in honor of John Alexander Logan (1826–1886), a U.S. Army general and U.S. Senator from Illinois.	20,619	1,845.31 sq mi (4,779 km2)
Mesa County	077	Grand Junction	1883-02-14	Split from Gunnison County.	Named for the mesa formations which are widespread through the area.	159,681	3,345.69 sq mi (8,665 km2)
Mineral County	079	Creede	1893-03-27	Split from Hinsdale, Rio Grande, and Saguache counties.	Named from the plentiful mineral deposits found in the area.	944	878.16 sq mi (2,274 km2)
Moffat County	081	Craig	1911-02-27	Split from Routt County.	Named in honor of railroad pioneer David H. Moffat.	13,327	4,755.86 sq mi (12,318 km2)
Montezuma County	083	Cortez	1889-04-16	Split from La Plata County.	Named in honor of Aztec leader Moctezuma II. Ruins in the area were once thought to be Aztec.	26,531	2,035.80 sq mi (5,273 km2)
Montrose County	085	Montrose	1883-02-11	Split from Gunnison County.	Named for the town of Montrose, which in turn was probably named from the novel A Legend of Montrose, published in 1819 by Walter Scott.	44,156	2,246.43 sq mi (5,818 km2)
Morgan County	087	Fort Morgan	1889-02-19	Split from Weld County.	Named for old Fort Morgan, which in turn was named in honor of U.S. Army Colonel Christopher A. Morgan.	29,524	1,293.83 sq mi (3,351 km2)
Otero County	089	La Junta	1889-03-25	Split from Bent County.	Named in honor of Miguel A. Otero of the prominent Otero family of the Southwest.	18,136	1,267.66 sq mi (3,283 km2)
Ouray County	091	Ouray	1877-01-18	Split from Hinsdale and Lake counties. Renamed Uncompaghre County for four days from 1883-02-27, to 1883-03-02.	Named in honor of Ouray, a Ute Native American leader.	5,176	542.30 sq mi (1,405 km2)
Park County	093	Fairplay	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for South Park which occupies most of the county.	18,117	2,209.36 sq mi (5,722 km2)
Phillips County	095	Holyoke	1889-03-27	Split from Logan County.	Named in honor of R.O. Phillips, secretary of the Lincoln Land Company, which sold farmsteads in the area.	4,476	688.30 sq mi (1,783 km2)
Pitkin County	097	Aspen	1881-02-23	Split from Gunnison County.	Named in honor of Frederick Walker Pitkin, the second Governor of the State of Colorado.	16,640	970.37 sq mi (2,513 km2)
Prowers County	099	Lamar	1889-04-11	Split from Bent County.	Named in honor of John W. Prowers, a pioneer of the Arkansas River valley.	11,751	1,645.37 sq mi (4,261 km2)
Pueblo County	101	Pueblo	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for historic town of Pueblo. Pueblo is a Spanish word meaning village or people.	169,422	2,396.77 sq mi (6,208 km2)
Rio Blanco County	103	Meeker	1889-03-25	Split from Garfield County.	Named for the White River, which was originally named Rio Blanco in Spanish.	6,569	3,226.24 sq mi (8,356 km2)
Rio Grande County	105	Del Norte	1874-02-10	Split from Costilla County and Conejos County counties.	Named for the Rio Grande, which flows through the area.	11,188	913.10 sq mi (2,365 km2)
Routt County	107	Steamboat Springs	1877-01-29	Split from Grand County.	Named in honor of John Long Routt, the first Governor of the State of Colorado.	25,064	2,362.11 sq mi (6,118 km2)
Saguache County	109	Saguache	1866-12-29	Split from Lake and Costilla counties.	Name comes from a Ute language noun meaning "sand dunes".[c][11]	6,688	3,168.32 sq mi (8,206 km2)
San Juan County	111	Silverton	1876-01-31	Split from Lake County.	Named for the San Juan River and San Juan Mountains, which in turn were named for Saint John the Evangelist.	705	388.99 sq mi (1,007 km2)
San Miguel County	113	Telluride	1883-03-02	Split from San Juan County.	Named for the San Miguel River and San Miguel Mountains, which in turn were named for Saint Michael the Archangel.	7,868	1,290.76 sq mi (3,343 km2)
Sedgwick County	115	Julesburg	1889-04-09	Split from Logan County.	Named for Fort Sedgwick, which, in turn, was named for U.S. Army General John Sedgwick (1813–1864).	2,299	548.83 sq mi (1,421 km2)
Summit County	117	Breckenridge	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named for the many high mountain summits in the area.	30,465	618.92 sq mi (1,603 km2)
Teller County	119	Cripple Creek	1899-03-23	Split from El Paso and Fremont counties.	Named in honor of Henry Moore Teller, a U.S. Senator from Colorado and United States Secretary of the Interior.	24,617	558.58 sq mi (1,447 km2)
Washington County	121	Akron	1887-02-09	Split from Weld County.	Named in honor of George Washington (1732–1799), the first President of the United States.	4,855	2,522.90 sq mi (6,534 km2)
Weld County	123	Greeley	1861-11-01	Created as one of the 17 original counties of the Territory of Colorado.	Named in honor of Lewis Ledyard Weld, the first Secretary of the Territory of Colorado.	359,442	4,013.84 sq mi (10,396 km2)
Yuma County	125	Wray	1889-03-15	Split from Washington County.	Named for the Quechan (Yuma) Nation of Native Americans.	9,862	2,369.61 sq mi (6,137 km2)

For United States Census Bureau population estimates for Colorado counties as of July 1, 2023, see the List of Colorado counties by population.^[d] That list ranks the counties by 2023 population and includes population changes since the 2000 United States Census. That list also includes the county websites, links to Colorado Department of Transportation county maps, and the geographic coordinates of the counties.

As of July 1, 2023, El Paso County remains the most populous county in Colorado with a population estimate of 744,215, while Hinsdale County with a 2023 population of 765 is now the least populous.^[d] Five of the 64 Colorado counties now have more than 500,000 residents, while 12 counties have fewer than 5,000 residents.^[d]

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^[13] 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.^[e]

Of the 64 Colorado counties, 20 counties extend above 14,000 feet (4,267 m) elevation, 32 counties extend above 13,000 feet (3,962 m), 42 counties extend above 10,000 feet (3,048 m), and all 64 Colorado counties extend above 4,116 feet (1,255 m).

Of Colorado's 64 counties, 4 counties have a mean elevation^[f] above 11,000 feet (3,353 m) elevation, 22 counties have a mean elevation above 10,000 feet (3,048 m), 32 counties have a mean elevation above 9,000 feet (2,743 m), and all 64 counties have a mean elevation above 3,880 feet (1,183 m).

The following 13 Colorado counties have highest mean elevation of any county in the United States, exceeding even the Denali Borough of Alaska.

1. Costilla County was the first area within the present State of Colorado to be settled by Europeans in 1851.

2. Taos County, created by the Territory of New Mexico in 1852, was the first organized county to extend into the area of the present State of Colorado.

3. Arapahoe County, created by the Territory of Kansas in 1855, was the first county created exclusively within the area of the present State of Colorado.

4. On November 28, 1859, the extralegal Territory of Jefferson created 12 counties:^[13]

5. On November 1, 1861, the Territory of Colorado created the 17 original Colorado counties:

6. Of the 17 original Colorado counties created in 1861, only Gilpin County and Clear Creek County have retained their original boundaries with only minor survey changes.

7. Guadaloupe County was the first Colorado county to be renamed after only six days in 1861.

8. Las Animas County was the first new Colorado county to be created (in 1866) after the original 17 counties.

9. Greenwood County was the longest lived former Colorado county, existing four years from 1870 to 1874.

10. In 1876, San Juan County became the last county created by the Territory of Colorado, bringing the total number of territorial counties to 26.

11. In 1877, Ouray County became the first county created by the new State of Colorado.

12. Carbonate County was the shortest lived former Colorado county, existing only two days in 1879 before being dissolved.

13. The City and County of Broomfield became the newest Colorado county in 2001, bring the total number of counties to 64.

1. El Paso County (88) and the City and County of Denver (93) and are among the 100 most populous counties of the United States.

2. San Juan County (16), Hinsdale County (25), Mineral County (32), Jackson County (55), Kiowa County (59), and Cheyenne County (80) are among the 100 least populous counties of the United States.

3. Jefferson County borders ten adjacent counties, the most of any Colorado county.^[k]

4. Delta County and the City and County of Denver each border only three adjacent counties, the fewest of Colorado counties.^[l]

5. Weld County has the most incorporated municipalities of any Colorado county with 31.

6. The following nine Colorado counties have no incorporated municipalities other than their county seat:

7. Of all 64 Colorado counties, only Conejos County has a county seat that is not an incorporated municipality.

8. The City and County of Denver and the City and County of Broomfield are the only two Colorado counties with enclaves. Arapahoe County, Boulder County, and Jefferson County are the only three Colorado counties with exclaves.

9. Pitkin and Weld are the only home rule counties.

• The ten most populous Colorado counties
•  
  1. The United States Air Force Academy in El Paso County, Colorado
•  
  2. The Colorado State Capitol in the City and County of Denver
•  
  3. A bank building in Arapahoe County, Colorado
•  
  4. The Colorado School of Mines in Jefferson County, Colorado
•  
  5. The Anschutz Medical Campus in Adams County, Colorado
•  
  6. Roxborough State Park in Douglas County, Colorado
•  
  7. Colorado State University in Larimer County, Colorado
•  
  8. The Greeley Stampede Parade in Weld County, Colorado
•  
  9. The National Center for Atmospheric Research in Boulder County, Colorado
•  
  10. The Historic Arkansas Riverwalk in Pueblo County, Colorado

• Bibliography of Colorado
• Geography of Colorado
• History of Colorado
• Index of Colorado-related articles
• List of Colorado-related lists
  • List of Colorado counties by per capita income
  • List of Colorado counties by population
  • List of Colorado counties by socioeconomic factors
  • List of Colorado county high points
  • List of county courthouses in Colorado
  • List of county seats in Colorado

Outline of Colorado

• United States Department of Commerce
  • United States Census Bureau
• State of Colorado
  • Department of Local Affairs
• Colorado County Clerks Association
• History Colorado

38°59′50″N 105°32′52″W / 38.9972°N 105.5478°W / 38.9972; -105.5478 (State of Colorado)