List of counties in Colorado

The U.S. State of Colorado is divided into 64 counties.^[1] 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.^[2] 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 location of the State of Colorado in the United States of America.

Adams

Alamosa

Arapahoe

Archuleta

Baca

Bent

Boulder

Broomfield

Chaffee

Cheyenne

Clear Creek

Conejos

Costilla

Crowley

Custer

Delta

Denver

Dolores

Douglas

Eagle

Elbert

El Paso

Fremont

Garfield

Gilpin

Grand

Gunnison

Hinsdale

Huerfano

Jackson

Jefferson

Kiowa

Kit
Carson

Lake

La Plata

Larimer

Las Animas

Lincoln

Logan

Mesa

Mineral

Moffat

Montezuma

Montrose

Morgan

Otero

Ouray

Park

Phillips

Pitkin

Prowers

Pueblo

Rio Blanco

Rio Grande

Routt

Saguache

San Juan

San Miguel

Sedgwick

Summit

Teller

Washington

Weld

Yuma

The 64 counties of the U.S. State of Colorado.

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.^[a] Five of the 64 Colorado counties now have more than 500,000 residents, while 12 counties have fewer than 5,000 residents.^[a]

Las Animas County, 4,776 square miles (12,369 km²) in area, is the most extensive county, while the City and County of Broomfield, 34 square miles (87 km²) in area, is the least extensive. The City and County of Denver was the most densely populated Colorado county, with a 2024 population density of 4,918 residents per square mile of land area (1,899/km²), while Hinsdale County was the least densely populated county, with a 2024 population density of 0.67 resident per square mile of land area (0.26/km²).

Mount Elbert, the highest summit of Colorado and the entire Rocky Mountains at an elevation of 14,440 feet (4,401.2 m), is located in Lake County. The lowest point in Colorado is where the Arikaree River flows out of Yuma County and into Kansas, at 3,317 feet (1,011 m) elevation.^[b] 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.^[4]

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.^[5][6] 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.^[7] 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.

For Colorado counties by statistical area, see the List of statistical areas in Colorado.

For Colorado county seats, see the List of county seats in Colorado.

For Colorado county courthouses, see the List of Colorado county courthouses.

For Colorado county per capita income, see the List of Colorado counties by per capita income

For Colorado county socioeconomics, see the List of Colorado counties by socioeconomic factors.

For Colorado county highest elevation points, see the List of Colorado county high points.

For Colorado municipalities by county, see the List of Colorado municipalities by county.

For Colorado populated places by county, see the List of Colorado populated places by county.

For Colorado county maps, see the State of Colorado Map Viewer.

County	FIPS code[8][c]	County seat[9][10]	Est.[11]	Formed from[11]	Etymology[11]	Population[12]	Area[9]	Map
Adams County	001	Brighton	Nov 15, 1902	Split from Arapahoe County.	Named in honor of Alva Adams, the 5th, 10th, and 14th Governor of the State of Colorado.	542,973	1,182.29 sq mi (3,062 km2)
Alamosa County	003	Alamosa	Mar 8, 1913	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.	16,689	723.21 sq mi (1,873 km2)
Arapahoe County	005	Littleton	Nov 1, 1861	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.	666,918	804.41 sq mi (2,083 km2)
Archuleta County	007	Pagosa Springs	Apr 14, 1885	Split from Conejos County.	Named in honor of Colorado State Senator Antonio D. Archuleta and his father, José Manuel Archuleta.	14,112	1,354.53 sq mi (3,508 km2)
Baca County	009	Springfield	Apr 16, 1889	Split from Las Animas County.	Named in honor of pioneer and Colorado territorial legislator Felipe Baca.	3,367	2,558.48 sq mi (6,626 km2)
Bent County	011	Las Animas	Feb 11, 1870	Split from Huerfano County and former Cheyenne and Arapaho tribal land.	Named in honor of frontier trader William Bent.	5,779	1,541.07 sq mi (3,991 km2)
Boulder County	013	Boulder	Nov 1, 1861	Created as one of the 17 original counties of the Territory of Colorado.	Named for the abundance of granite boulders along Boulder Creek.	330,262	740.48 sq mi (1,918 km2)
City and County of Broomfield	014	Broomfield	Nov 15, 2001	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.	78,323	33.57 sq mi (87 km2)
Chaffee County	015	Salida	Feb 10, 1879	Split from Carbonate County.	Named in honor of Jerome Bunty Chaffee, one of Colorado's first two U.S. Senators from 1876 to 1879.	20,780	1,014.12 sq mi (2,627 km2)
Cheyenne County	017	Cheyenne Wells	Mar 25, 1889	Split from Elbert and Bent counties.	Named for the Cheyenne Nation of Native Americans.	1,712	1,781.90 sq mi (4,615 km2)
Clear Creek County	019	Georgetown	Nov 1, 1861	Created as one of the 17 original counties of the Territory of Colorado.	Named for Clear Creek which originates in the county.	9,076	396.53 sq mi (1,027 km2)
Conejos County	021	Conejos	Nov 1, 1861	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.	7,549	1,290.22 sq mi (3,342 km2)
Costilla County	023	San Luis	Nov 1, 1861	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.	3,686	1,229.38 sq mi (3,184 km2)
Crowley County	025	Ordway	May 29, 1911	Split from Otero County.	Named in honor of Colorado State Senator John H. Crowley.	5,600	800.27 sq mi (2,073 km2)
Custer County	027	Westcliffe	Mar 9, 1877	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.	5,553	739.24 sq mi (1,915 km2)
Delta County	029	Delta	Feb 11, 1883	Split from Gunnison County.	Named for the town of Delta located at the delta of the Uncompahgre River.	32,215	1,149.44 sq mi (2,977 km2)
City and County of Denver	031	Denver	Dec 1, 1902	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.	729,019	155.66 sq mi (403 km2)
Dolores County	033	Dove Creek	Mar 4, 1881	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.	2,467	1,076.93 sq mi (2,789 km2)
Douglas County	035	Castle Rock	Nov 1, 1861	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.	393,995	842.30 sq mi (2,182 km2)
Eagle County	037	Eagle	Feb 11, 1883	Split from Summit County.	Named for the Eagle River which originates in the county.	54,330	1,700.76 sq mi (4,405 km2)
El Paso County	041	Colorado Springs	Nov 1, 1861	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.	752,772	2,128.60 sq mi (5,513 km2)
Elbert County	039	Kiowa	Feb 2, 1874	Split from Douglas County.	Named in honor of Samuel Hitt Elbert, the sixth Governor of the Territory of Colorado.	29,382	1,849.08 sq mi (4,789 km2)
Fremont County	043	Cañon City	Nov 1, 1861	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.	50,093	1,533.09 sq mi (3,971 km2)
Garfield County	045	Glenwood Springs	Feb 10, 1883	Split from Summit County.	Named in honor of James Abram Garfield (1831–1881), the twentieth President of the United States.	63,167	2,958.23 sq mi (7,662 km2)
Gilpin County	047	Central City	Nov 1, 1861	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.	5,963	150.15 sq mi (389 km2)
Grand County	049	Hot Sulphur Springs	Feb 2, 1874	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.	16,154	1,868.53 sq mi (4,839 km2)
Gunnison County	051	Gunnison	Mar 9, 1877	Split from Lake County.	Named in honor of John Williams Gunnison, the U.S. Army captain who explored the region.	17,310	3,259.22 sq mi (8,441 km2)
Hinsdale County	053	Lake City	Feb 10, 1874	Split from Lake, Conejos, and Costilla counties.	Named in honor of George Aaron Hinsdale, a Lieutenant Governor of the Territory of Colorado.	747	1,123.35 sq mi (2,909 km2)
Huerfano County	055	Walsenburg	Nov 1, 1861	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.	6,988	1,592.37 sq mi (4,124 km2)
Jackson County	057	Walden	May 5, 1909	Split from Larimer County.	Named in honor of Andrew Jackson (1767–1845), the seventh President of the United States.	1,273	1,619.75 sq mi (4,195 km2)
Jefferson County	059	Golden	Nov 1, 1861	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.	578,533	772.85 sq mi (2,002 km2)
Kiowa County	061	Eads	Apr 11, 1889	Split from Bent County.	Named for the Kiowa Nation of Native Americans.	1,392	1,785.90 sq mi (4,625 km2)
Kit Carson County	063	Burlington	Apr 11, 1889	Split from Elbert County.	Named in honor of Christopher Houston "Kit" Carson, the famous frontier scout and soldier.	7,080	2,162.43 sq mi (5,601 km2)
La Plata County	067	Durango	Feb 10, 1874	Split from Lake and Conejos counties.	Named for the many silver deposits in the area. La plata is a Spanish expression for the silver.	56,823	1,700.44 sq mi (4,404 km2)
Lake County	065	Leadville	Nov 1, 1861	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.	7,369	383.55 sq mi (993 km2)
Larimer County	069	Fort Collins	Nov 1, 1861	Created as one of the 17 original counties of the Territory of Colorado.	Named in honor of William Larimer, a pioneer entrepreneur.	374,574	2,631.75 sq mi (6,816 km2)
Las Animas County	071	Trinidad	Feb 9, 1866	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.	14,518	4,773.27 sq mi (12,363 km2)
Lincoln County	073	Hugo	Apr 11, 1889	Split from Elbert and Bent counties.	Named in honor of Abraham Lincoln (1809–1865), the sixteenth President of the United States.	5,598	2,585.21 sq mi (6,696 km2)
Logan County	075	Sterling	Feb 25, 1887	Split from Weld County.	Named in honor of John Alexander Logan (1826–1886), a U.S. Army general and U.S. Senator from Illinois.	20,755	1,845.31 sq mi (4,779 km2)
Mesa County	077	Grand Junction	Feb 14, 1883	Split from Gunnison County.	Named for the mesa formations which are widespread through the area.	161,260	3,345.69 sq mi (8,665 km2)
Mineral County	079	Creede	Mar 27, 1893	Split from Hinsdale, Rio Grande, and Saguache counties.	Named from the plentiful mineral deposits found in the area.	933	878.16 sq mi (2,274 km2)
Moffat County	081	Craig	Feb 27, 1911	Split from Routt County.	Named in honor of railroad pioneer David H. Moffat.	13,142	4,755.86 sq mi (12,318 km2)
Montezuma County	083	Cortez	Apr 16, 1889	Split from La Plata County.	Named in honor of Aztec leader Moctezuma II. Ruins in the area were once thought to be Aztec.	26,841	2,035.80 sq mi (5,273 km2)
Montrose County	085	Montrose	Feb 11, 1883	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.	44,806	2,246.43 sq mi (5,818 km2)
Morgan County	087	Fort Morgan	Feb 19, 1889	Split from Weld County.	Named for old Fort Morgan, which in turn was named in honor of U.S. Army Colonel Christopher A. Morgan.	30,300	1,293.83 sq mi (3,351 km2)
Otero County	089	La Junta	Mar 25, 1889	Split from Bent County.	Named in honor of Miguel A. Otero of the prominent Otero family of the Southwest.	17,991	1,267.66 sq mi (3,283 km2)
Ouray County	091	Ouray	Jan 18, 1877	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.	5,197	542.30 sq mi (1,405 km2)
Park County	093	Fairplay	Nov 1, 1861	Created as one of the 17 original counties of the Territory of Colorado.	Named for South Park which occupies most of the county.	18,316	2,209.36 sq mi (5,722 km2)
Phillips County	095	Holyoke	Mar 27, 1889	Split from Logan County.	Named in honor of R.O. Phillips, secretary of the Lincoln Land Company, which sold farmsteads in the area.	4,488	688.30 sq mi (1,783 km2)
Pitkin County	097	Aspen	Feb 23, 1881	Split from Gunnison County.	Named in honor of Frederick Walker Pitkin, the second Governor of the State of Colorado.	16,643	970.37 sq mi (2,513 km2)
Prowers County	099	Lamar	Apr 11, 1889	Split from Bent County.	Named in honor of John W. Prowers, a pioneer of the Arkansas River valley.	11,957	1,645.37 sq mi (4,261 km2)
Pueblo County	101	Pueblo	Nov 1, 1861	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.	169,866	2,396.77 sq mi (6,208 km2)
Rio Blanco County	103	Meeker	Mar 25, 1889	Split from Garfield County.	Named for the White River, which was originally named Rio Blanco in Spanish.	6,607	3,226.24 sq mi (8,356 km2)
Rio Grande County	105	Del Norte	Feb 10, 1874	Split from Costilla County and Conejos County counties.	Named for the Rio Grande, which flows through the area.	11,132	913.10 sq mi (2,365 km2)
Routt County	107	Steamboat Springs	Jan 29, 1877	Split from Grand County.	Named in honor of John Long Routt, the first Governor of the State of Colorado.	25,243	2,362.11 sq mi (6,118 km2)
Saguache County	109	Saguache	Dec 29, 1866	Split from Lake and Costilla counties.	Name comes from a Ute language noun meaning "sand dunes".[d][13]	6,670	3,168.32 sq mi (8,206 km2)
San Juan County	111	Silverton	Jan 31, 1876	Split from Lake County.	Named for the San Juan River and San Juan Mountains, which in turn were named for Saint John the Evangelist.	821	388.99 sq mi (1,007 km2)
San Miguel County	113	Telluride	Mar 2, 1883	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.	7,819	1,290.76 sq mi (3,343 km2)
Sedgwick County	115	Julesburg	Apr 9, 1889	Split from Logan County.	Named for Fort Sedgwick, which, in turn, was named for U.S. Army General John Sedgwick (1813–1864).	2,257	548.83 sq mi (1,421 km2)
Summit County	117	Breckenridge	Nov 1, 1861	Created as one of the 17 original counties of the Territory of Colorado.	Named for the many high mountain summits in the area.	30,882	618.92 sq mi (1,603 km2)
Teller County	119	Cripple Creek	Mar 23, 1899	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.	24,862	558.58 sq mi (1,447 km2)
Washington County	121	Akron	Feb 9, 1887	Split from Weld County.	Named in honor of George Washington (1732–1799), the first President of the United States.	4,771	2,522.90 sq mi (6,534 km2)
Weld County	123	Greeley	Nov 1, 1861	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.	369,745	4,013.84 sq mi (10,396 km2)
Yuma County	125	Wray	Mar 15, 1889	Split from Washington County.	Named for the Quechan (Yuma) Nation of Native Americans.	10,048	2,369.61 sq mi (6,137 km2)

County population

The 64 Counties of the State of Colorado Ranked by Population

County[1]	Population[14]								County website	Coordinates[e]
	2024 rank	2024 estimates[a]	Change	2020 Census	Change	2010 Census	Change	2000 Census
El Paso County	1	752,772	+3.06%	730,395	+17.38%	622,263	+20.38%	516,934	El Paso County	38.8320°N 104.5254°W / 38.8320; -104.5254 (El Paso County, Colorado)
City and County of Denver	2	729,019	+1.89%	715,522	+19.22%	600,158	+8.37%	553,805	City and County of Denver	39.7620°N 104.8760°W / 39.7620; -104.8760 (City and County of Denver, Colorado)
Arapahoe County	3	666,918	+1.81%	655,070	+14.52%	572,003	+17.01%	488,829	Arapahoe County	39.6503°N 104.3393°W / 39.6503; -104.3393 (Arapahoe County, Colorado)
Jefferson County	4	578,533	−0.75%	582,910	+9.05%	534,543	+1.73%	525,449	Jefferson County	39.5859°N 105.2506°W / 39.5859; -105.2506 (Jefferson County, Colorado)
Adams County	5	542,973	+4.50%	519,572	+17.66%	441,603	+26.87%	348,076	Adams County	39.8742°N 104.3378°W / 39.8742; -104.3378 (Adams County, Colorado)
Douglas County	6	393,995	+10.06%	357,978	+25.40%	285,465	+62.44%	175,732	Douglas County	39.3296°N 104.9297°W / 39.3296; -104.9297 (Douglas County, Colorado)
Larimer County	7	374,574	+4.32%	359,066	+19.84%	299,630	+19.14%	251,494	Larimer County	40.6662°N 105.4607°W / 40.6662; -105.4607 (Larimer County, Colorado)
Weld County	8	369,745	+12.39%	328,981	+30.12%	252,825	+39.86%	180,766	Weld County	40.5542°N 104.3938°W / 40.5542; -104.3938 (Weld County, Colorado)
Boulder County	9	330,262	−0.15%	330,758	+12.29%	294,567	+9.19%	269,784	Boulder County	40.0925°N 105.3577°W / 40.0925; -105.3577 (Boulder County, Colorado)
Pueblo County	10	169,866	+1.01%	168,162	+5.72%	159,063	+12.42%	141,490	Pueblo County	38.1732°N 104.5128°W / 38.1732; -104.5128 (Pueblo County, Colorado)
Mesa County	11	161,260	+3.57%	155,703	+6.12%	146,723	+25.47%	116,939	Mesa County	39.0182°N 108.4677°W / 39.0182; -108.4677 (Mesa County, Colorado)
City and County of Broomfield	12	78,323	+5.68%	74,112	+32.61%	55,889	+42.57%	39,202	City and County of Broomfield	39.9541°N 105.0527°W / 39.9541; -105.0527 (City and County of Broomfield, Colorado)
Garfield County	13	63,167	+2.40%	61,685	+9.39%	56,389	+28.78%	43,786	Garfield County	39.6003°N 107.9052°W / 39.6003; -107.9052 (Garfield County, Colorado)
La Plata County	14	56,823	+2.13%	55,638	+8.38%	51,334	+16.78%	43,957	La Plata County	37.2864°N 107.8436°W / 37.2864; -107.8436 (La Plata County, Colorado)
Eagle County	15	54,330	−2.51%	55,731	+6.77%	52,197	+25.40%	41,623	Eagle County	39.6277°N 106.6951°W / 39.6277; -106.6951 (Eagle County, Colorado)
Fremont County	16	50,093	+2.36%	48,939	+4.52%	46,824	+1.48%	46,140	Fremont County	38.4732°N 105.4394°W / 38.4732; -105.4394 (Fremont County, Colorado)
Montrose County	17	44,806	+4.98%	42,679	+3.40%	41,276	+23.44%	33,438	Montrose County	38.4027°N 108.2702°W / 38.4027; -108.2702 (Montrose County, Colorado)
Delta County	18	32,215	+3.27%	31,196	+0.79%	30,952	+11.24%	27,824	Delta County	38.8614°N 107.8632°W / 38.8614; -107.8632 (Delta County, Colorado)
Summit County	19	30,882	−0.56%	31,055	+10.93%	27,994	+18.82%	23,560	Summit County	39.6340°N 106.1160°W / 39.6340; -106.1160 (Summit County, Colorado)
Morgan County	20	30,300	+4.08%	29,111	+3.38%	28,159	+3.63%	27,172	Morgan County	40.2626°N 103.8098°W / 40.2626; -103.8098 (Morgan County, Colorado)
Elbert County	21	29,382	+12.74%	26,062	+12.89%	23,086	+16.27%	19,855	Elbert County	39.2864°N 104.1355°W / 39.2864; -104.1355 (Elbert County, Colorado)
Montezuma County	22	26,841	+3.84%	25,849	+1.23%	25,535	+7.19%	23,822	Montezuma County	37.3383°N 108.5970°W / 37.3383; -108.5970 (Montezuma County, Colorado)
Routt County	23	25,243	+1.67%	24,829	+5.61%	23,509	+19.46%	19,679	Routt County	40.4841°N 106.9908°W / 40.4841; -106.9908 (Routt County, Colorado)
Teller County	24	24,862	+0.62%	24,710	+5.82%	23,350	+13.68%	20,541	Teller County	38.8822°N 105.1617°W / 38.8822; -105.1617 (Teller County, Colorado)
Chaffee County	25	20,780	+6.70%	19,476	+9.36%	17,809	+9.59%	16,250	Chaffee County	38.7466°N 106.1938°W / 38.7466; -106.1938 (Chaffee County, Colorado)
Logan County	26	20,755	−3.59%	21,528	−5.20%	22,709	+10.42%	20,566	Logan County	40.7246°N 103.1101°W / 40.7246; -103.1101 (Logan County, Colorado)
Park County	27	18,316	+5.32%	17,390	+7.31%	16,206	+11.62%	14,519	Park County	39.1188°N 105.7171°W / 39.1188; -105.7171 (Park County, Colorado)
Otero County	28	17,991	−3.74%	18,690	−0.75%	18,831	−7.29%	20,311	Otero County	37.9026°N 103.7166°W / 37.9026; -103.7166 (Otero County, Colorado)
Gunnison County	29	17,310	+2.32%	16,918	+10.40%	15,324	+9.46%	14,000	Gunnison County	38.6664°N 107.0319°W / 38.6664; -107.0319 (Gunnison County, Colorado)
Alamosa County	30	16,689	+1.91%	16,376	+6.03%	15,445	+3.21%	14,965	Alamosa County	37.5728°N 105.7884°W / 37.5728; -105.7884 (Alamosa County, Colorado)
Pitkin County	31	16,643	−4.12%	17,358	+1.22%	17,148	+15.17%	14,889	Pitkin County	39.2172°N 106.9165°W / 39.2172; -106.9165 (Pitkin County, Colorado)
Grand County	32	16,154	+2.78%	15,717	+5.89%	14,843	+19.38%	12,433	Grand County	40.1025°N 106.1181°W / 40.1025; -106.1181 (Grand County, Colorado)
Las Animas County	33	14,518	−0.25%	14,555	−6.14%	15,507	+1.94%	15,212	Las Animas County	37.3166°N 104.0391°W / 37.3166; -104.0391 (Las Animas County, Colorado)
Archuleta County	34	14,112	+5.64%	13,359	+10.55%	12,084	+22.13%	9,894	Archuleta County	37.1937°N 107.0481°W / 37.1937; -107.0481 (Archuleta County, Colorado)
Moffat County	35	13,142	−1.13%	13,292	−3.65%	13,795	+4.68%	13,178	Moffat County	40.6187°N 108.2075°W / 40.6187; -108.2075 (Moffat County, Colorado)
Prowers County	36	11,957	−0.35%	11,999	−4.40%	12,551	−13.34%	14,483	Prowers County	37.9549°N 102.3934°W / 37.9549; -102.3934 (Prowers County, Colorado)
Rio Grande County	37	11,132	−3.53%	11,539	−3.70%	11,982	−3.57%	12,425	Rio Grande County	37.5825°N 106.3832°W / 37.5825; -106.3832 (Rio Grande County, Colorado)
Yuma County	38	10,048	+0.60%	9,988	−0.55%	10,043	+2.00%	9,846	Yuma County	40.0022°N 102.4243°W / 40.0022; -102.4243 (Yuma County, Colorado)
Clear Creek County	39	9,076	−3.42%	9,397	+3.40%	9,088	−1.89%	9,263	Clear Creek County	39.6891°N 105.6443°W / 39.6891; -105.6443 (Clear Creek County, Colorado)
San Miguel County	40	7,819	−3.13%	8,072	+9.69%	7,359	+11.62%	6,593	San Miguel County	38.0042°N 108.4057°W / 38.0042; -108.4057 (San Miguel County, Colorado)
Conejos County	41	7,549	+1.18%	7,461	−9.63%	8,256	−1.71%	8,400	Conejos County	37.2008°N 106.1915°W / 37.2008; -106.1915 (Conejos County, Colorado)
Lake County	42	7,369	−0.90%	7,436	+1.72%	7,310	−6.45%	7,814	Lake County	39.2023°N 106.3449°W / 39.2023; -106.3449 (Lake County, Colorado)
Kit Carson County	43	7,080	−0.10%	7,087	−14.30%	8,270	+3.21%	8,013	Kit Carson County	39.3056°N 102.6029°W / 39.3056; -102.6029 (Kit Carson County, Colorado)
Huerfano County	44	6,988	+2.46%	6,820	+1.62%	6,711	−14.61%	7,859	Huerfano County	37.6847°N 104.9605°W / 37.6847; -104.9605 (Huerfano County, Colorado)
Saguache County	45	6,670	+4.74%	6,368	+4.26%	6,108	+3.46%	5,904	Saguache County	38.0807°N 106.2809°W / 38.0807; -106.2809 (Saguache County, Colorado)
Rio Blanco County	46	6,607	+1.19%	6,529	−2.06%	6,666	+11.25%	5,992	Rio Blanco County	39.9807°N 108.2179°W / 39.9807; -108.2179 (Rio Blanco County, Colorado)
Gilpin County	47	5,963	+2.67%	5,808	+6.75%	5,441	+14.64%	4,746	Gilpin County	39.8575°N 105.5226°W / 39.8575; -105.5226 (Gilpin County, Colorado)
Bent County	48	5,779	+2.28%	5,650	−13.06%	6,499	+8.39%	5,996	Bent County	37.9548°N 103.0717°W / 37.9548; -103.0717 (Bent County, Colorado)
Crowley County	49	5,600	−5.44%	5,922	+1.70%	5,823	+5.60%	5,514	Crowley County	38.3266°N 103.7848°W / 38.3266; -103.7848 (Crowley County, Colorado)
Lincoln County	50	5,598	−1.36%	5,675	+3.80%	5,467	−10.22%	6,089	Lincoln County	38.9870°N 103.5146°W / 38.9870; -103.5146 (Lincoln County, Colorado)
Custer County	51	5,553	+18.05%	4,704	+10.55%	4,255	+21.29%	3,508	Custer County	38.1087°N 105.3674°W / 38.1087; -105.3674 (Custer County, Colorado)
Ouray County	52	5,197	+6.63%	4,874	+9.87%	4,436	+18.39%	3,747	Ouray County	38.1554°N 107.7691°W / 38.1554; -107.7691 (Ouray County, Colorado)
Washington County	53	4,771	−0.95%	4,817	+0.06%	4,814	−2.19%	4,922	Washington County	39.9704°N 103.2016°W / 39.9704; -103.2016 (Washington County, Colorado)
Phillips County	54	4,488	−0.93%	4,530	+1.98%	4,442	−0.96%	4,485	Phillips County	40.5939°N 102.3576°W / 40.5939; -102.3576 (Phillips County, Colorado)
Costilla County	55	3,686	+5.34%	3,499	−0.71%	3,524	−3.74%	3,661	Costilla County	37.2777°N 105.4284°W / 37.2777; -105.4284 (Costilla County, Colorado)
Baca County	56	3,367	−3.96%	3,506	−7.44%	3,788	−16.14%	4,517	Baca County	37.3191°N 102.5605°W / 37.3191; -102.5605 (Baca County, Colorado)
Dolores County	57	2,467	+6.06%	2,326	+12.69%	2,064	+11.93%	1,844	Dolores County	37.7520°N 108.5173°W / 37.7520; -108.5173 (Dolores County, Colorado)
Sedgwick County	58	2,257	−6.11%	2,404	+1.05%	2,379	−13.40%	2,747	Sedgwick County	40.8760°N 102.3518°W / 40.8760; -102.3518 (Sedgwick County, Colorado)
Cheyenne County	59	1,712	−2.06%	1,748	−4.79%	1,836	−17.63%	2,229	Cheyenne County	38.8282°N 102.6034°W / 38.8282; -102.6034 (Cheyenne County, Colorado)
Kiowa County	60	1,392	−3.73%	1,446	+3.43%	1,398	−13.81%	1,622	Kiowa County	38.4333°N 102.7405°W / 38.4333; -102.7405 (Kiowa County, Colorado)
Jackson County	61	1,273	−7.69%	1,379	−1.08%	1,394	−11.60%	1,577	Jackson County	40.6661°N 106.3424°W / 40.6661; -106.3424 (Jackson County, Colorado)
Mineral County	62	933	+7.86%	865	+21.49%	712	−14.32%	831	Mineral County	37.6687°N 106.9241°W / 37.6687; -106.9241 (Mineral County, Colorado)
San Juan County	63	821	+16.45%	705	+0.86%	699	+25.27%	558	San Juan County	37.7640°N 107.6762°W / 37.7640; -107.6762 (San Juan County, Colorado)
Hinsdale County	64	747	−5.20%	788	−6.52%	843	+6.44%	792	Hinsdale County	37.8208°N 107.3004°W / 37.8208; -107.3004 (Hinsdale County, Colorado)
State of Colorado	State	5,957,493	+3.18%	5,773,714	+14.80%	5,029,196	+16.92%	4,301,262	State of Colorado	38.9972°N 105.5478°W / 38.9972; -105.5478 (State of Colorado)

Former counties

Main article: History of Colorado

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^[16] 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.^[f]

Counties formerly within the area 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.

County high points

Main article: List of Colorado county high points

See also: List of highest U.S. county high points

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).

County mean elevation

Main article: List of highest counties in the United States

Of Colorado's 64 counties, 4 counties have a mean elevation^[g] 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.

The 13 highest mean elevation counties in the United States

Rank[h]	County	Mean elevation[g]	High point[17]	Highest elevation[18][17][19]	Low point[19]	Lowest elevation[19]	Elevation range[i]
1	Lake County	11,702.5 feet 3,567 m	Mount Elbert	14,440 feet 4,401 m	Arkansas River[j]	8,965 feet 2,733 m	5,475 feet 1,669 m
2	Hinsdale County	11,300 feet 3,444 m	Uncompahgre Peak	14,315 feet 4,363 m	Lake Fork Gunnison River	8,285 feet 2,525 m	6,030 feet 1,838 m
3	Mineral County	11,116 feet 3,388 m	Phoenix Peak	13,902 feet 4,237 m	Rio Grande	8,330 feet 2,539 m	5,572 feet 1,698 m
4	San Juan County	11,085 feet 3,379 m	Vermilion Peak	13,900 feet 4,237 m	Animas River	8,270 feet 2,521 m	5,630 feet 1,716 m
5	Summit County	10,935.5 feet 3,333 m	Grays Peak	14,276 feet 4,351 m	Blue River	7,595 feet 2,315 m	6,681 feet 2,036 m
6	Alamosa County	10,928.5 feet 3,331 m	Blanca Peak	14,351 feet 4,374 m	Rio Grande	7,506 feet 2,288 m	6,845 feet 2,086 m
7	Saguache County	10,915 feet 3,327 m	Crestone Peak	14,300 feet 4,359 m	San Luis Creek	7,530 feet 2,295 m	6,770 feet 2,063 m
8	Costilla County	10,865.5 feet 3,312 m	Blanca Peak	14,351 feet 4,374 m	Rio Grande	7,380 feet 2,249 m	6,971 feet 2,125 m
9	Park County	10,705.5 feet 3,263 m	Mount Lincoln	14,293 feet 4,357 m	South Platte River	7,118 feet 2,170 m	7,175 feet 2,187 m
10	Chaffee County	10,661 feet 3,249 m	Mount Harvard	14,427 feet 4,397 m	Arkansas River	6,895 feet 2,102 m	7,532 feet 2,296 m
11	Clear Creek County	10,608 feet 3,233 m	Grays Peak	14,276 feet 4,351 m	Clear Creek	6,940 feet 2,115 m	7,336 feet 2,236 m
12	Rio Grande County	10,402 feet 3,171 m	Bennett Peak	13,209 feet 4,026 m	Rock Creek	7,595 feet 2,315 m	5,614 feet 1,711 m
13	Jackson County	10,353 feet 3,156 m	Clark Peak	12,956 feet 3,949 m	North Platte River	7,750 feet 2,362 m	5,206 feet 1,587 m

County firsts

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:^[16]

The 12 counties of the
Territory of Jefferson

County	County Seat
Arapahoe County	Denver City
Cheyenne County
El Paso County	Colorado City
Fountain County	Pueblo
Heele County	La Porte
Jackson County	Boulder City
Jefferson County	Arapahoe City Golden City
Mountain County	Central City
North County
Park County	Tarryall City
Saint Vrain's CountySt. Vrain's County	Saint VrainSt. Vrain
Saratoga County	Breckinridge

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

The 17 original counties of the
Territory of Colorado

County	First County Seat
Arapahoe County	Denver City
Boulder County	Boulder City
Clear Creek County	Idaho
Costilla County	San Miguel[k]
Douglas County	Frankstown
El Paso County	Colorado City
Fremont County	Cañon City
Gilpin County	Central City
Guadaloupe County	Guadaloupe
Huerfano County	Autobees Plaza
Jefferson County	Golden City
Lake County	Oro City
Larimer County	La Porte
Park County	Tarryall City
Pueblo County	Pueblo
Summit County	Parkville
Weld County	Saint VrainSt. Vrain

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.

County distinctions

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.^[l]

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

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:

County	County Seat
Archuleta County	Town of Pagosa Springs
Bent County	City of Las Animas
City and County of Broomfield
City and County of Denver
Hinsdale County	Town of Lake City
Jackson County	Town of Walden
Lake County	City of Leadville
Mineral County	Town of Creede
San Juan County	Town of Silverton

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.

Gallery

• 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

See also

• Geography portal
• History portal
• United States portal
• Colorado portal

• 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 counties by statistical area
  • List of Colorado county high points
  • List of Colorado municipalities by county
  • List of Colorado populated places by county
  • List of county courthouses in Colorado
  • List of county seats in Colorado
• Outline of Colorado

Notes

1. United States Census Bureau estimates of county population as of July 1, 2024,^[3]
2. Elevations are adjusted to the North American Vertical Datum of 1988 (NAVD 88).
3. The ANSI INCITS 31:2009 county code is the five-digit code which uniquely identifies counties and county equivalents in the United States. The three-digit number is unique to each individual county within a state, but to be unique within the entire United States, it must be prefixed by the two-digit ANSI INCITS 31:2009 state code. This means that, for example, while Adams County, Colorado is 001, Belknap County, New Hampshire and Alachua County, Florida are also 001. To uniquely identify Adams County, Colorado, one must use the state code of 08 plus the county code of 001; therefore, the unique nationwide identifier for Adams County, Colorado is 08001. The links in the column INCITS are to the Census Bureau Info page for that county.
4. The name "Saguache" is pronounced /səˈwætʃ/. This name comes from the Ute language noun "sawup" /səˈwʌp/ meaning "sand dunes". The Spanish language version of this name is usually spelled "Saguache", while the English language version is usually spelled "Sawatch".
5. The centroid geographic coordinates of the county as determined by the United States Census Bureau.^[15]
6. No organized counties of the District of Louisiana, the Territory of Missouri, the extralegal State of Deseret, or the Territory of Nebraska existed within the present boundaries of the State of Colorado.
7. The "mean of extremes" elevation is the arithmetic mean of the highest and lowest elevations.
8. Rank among United States counties and county-equivalents by mean elevation.
9. The elevation range is the arithmetic difference between the highest and lowest elevations.
10. The point where the Arkansas River flows out of Lake County and into Chaffee County, Colorado, is the highest county low point in the United States at 8,965 feet (2,733 m) elevation.
11. San Miguel was the original seat of Costilla County. In 1863, the Costilla County seat was moved 17 miles (27 km) north to San Luis. It was not until 1869, that surveys revealed that San Miguel, now renamed Costilla, was actually located in the New Mexico Territory.
12. Jefferson County, Colorado borders Boulder County, the City and County of Broomfield, Adams County, the City and County of Denver, Arapahoe County, Douglas County, Teller County, Park County, Clear Creek County, and Gilpin County, Colorado.
13. Delta County, Colorado borders Gunnison County, Montrose County, and Mesa County, Colorado. The City and County of Denver, Colorado borders Adams County, Arapahoe County, and Jefferson County, Colorado.