List of counties in Colorado

thumb|340px|The location of the in the |alt=A map showing the location of the U.S. State of 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 757,040, as of July 1, 2025, while Hinsdale County with a population of 753 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 2025 population density of 4,758 residents per square mile of land area (1,838/km2), while Hinsdale County is the least densely populated county, with a 2025 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 , 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.

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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.

: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 population

{|class="wikitable sortable plainrowheaders"

|+<big>The 64 Counties of the State of Colorado Ranked by Population</big>

!scope=col rowspan=2|County

!scope=col rowspan=2|County website

!scope=col rowspan=2|Coordinates

!scope=col|2025 rank

!scope=col|2025 estimates

!scope=col|Change

!scope=col|2020 Census

!scope=col|Change

!scope=col|2010 Census

!scope=col|Change

!scope=col|2000 Census

!scope=row|El Paso County

|align=center|1

|El Paso County

!scope=row data-sort-value=Denver|City and County of Denver

|align=center|2

|City and County of Denver

!scope=row|Arapahoe County

|align=center|3

|Arapahoe County

!scope=row|Jefferson County

|align=center|4

|Jefferson County

!scope=row|Adams County

|align=center|5

|Adams County

!scope=row|Douglas County

|align=center|6

|Douglas County

!scope=row|Weld County

|align=center|7

|Weld County

!scope=row|Larimer County

|align=center|8

|Larimer County

!scope=row|Boulder County

|align=center|9

|Boulder County

!scope=row|Pueblo County

|align=center|10

|Pueblo County

!scope=row|Mesa County

|align=center|11

|Mesa County

!scope=row data-sort-value=Broomfield|City and County of Broomfield

|align=center|12

|City and County of Broomfield

!scope=row|Garfield County

|align=center|13

|Garfield County

!scope=row|La Plata County

|align=center|14

|La Plata County

!scope=row|Eagle County

|align=center|15

|Eagle County

!scope=row|Fremont County

|align=center|16

|Fremont County

!scope=row|Montrose County

|align=center|17

|Montrose County

!scope=row|Delta County

|align=center|18

|Delta County

!scope=row|Summit County

|align=center|19

|Summit County

!scope=row|Elbert County

|align=center|20

|Elbert County

!scope=row|Morgan County

|align=center|21

|Morgan County

!scope=row|Montezuma County

|align=center|22

|Montezuma County

!scope=row|Routt County

|align=center|23

|Routt County

!scope=row|Teller County

|align=center|24

|Teller County

!scope=row|Chaffee County

|align=center|25

|Chaffee County

!scope=row|Logan County

|align=center|26

|Logan County

!scope=row|Park County

|align=center|27

|Park County

!scope=row|Otero County

|align=center|28

|Otero County

!scope=row|Gunnison County

|align=center|29

|Gunnison County

!scope=row|Alamosa County

|align=center|30

|Alamosa County

!scope=row|Pitkin County

|align=center|31

|Pitkin County

!scope=row|Grand County

|align=center|32

|Grand County

!scope=row|Las Animas County

|align=center|33

|Las Animas County

!scope=row|Archuleta County

|align=center|34

|Archuleta County

!scope=row|Moffat County

|align=center|35

|Moffat County

!scope=row|Prowers County

|align=center|36

|Prowers County

!scope=row|Rio Grande County

|align=center|37

|Rio Grande County

!scope=row|Yuma County

|align=center|38

|Yuma County

!scope=row|Clear Creek County

|align=center|39

|Clear Creek County

!scope=row|San Miguel County

|align=center|40

|San Miguel County

!scope=row|Lake County

|align=center|41

|Lake County

!scope=row|Conejos County

|align=center|42

|Conejos County

!scope=row|Kit Carson County

|align=center|43

|Kit Carson County

!scope=row|Huerfano County

|align=center|44

|Huerfano County

!scope=row|Saguache County

|align=center|45

|Saguache County

!scope=row|Rio Blanco County

|align=center|46

|Rio Blanco County

!scope=row|Gilpin County

|align=center|47

|Gilpin County

!scope=row|Bent County

|align=center|48

|Bent County

!scope=row|Crowley County

|align=center|49

|Crowley County

!scope=row|Lincoln County

|align=center|50

|Lincoln County

!scope=row|Custer County

|align=center|51

|Custer County

!scope=row|Ouray County

|align=center|52

|Ouray County

!scope=row|Washington County

|align=center|53

|Washington County

!scope=row|Phillips County

|align=center|54

|Phillips County

!scope=row|Costilla County

|align=center|55

|Costilla County

!scope=row|Baca County

|align=center|56

|Baca County

!scope=row|Dolores County

|align=center|57

|Dolores County

!scope=row|Sedgwick County

|align=center|58

|Sedgwick County

!scope=row|Cheyenne County

|align=center|59

|Cheyenne County

!scope=row|Kiowa County

|align=center|60

|Kiowa County

!scope=row|Jackson County

|align=center|61

|Jackson County

!scope=row|Mineral County

|align=center|62

|Mineral County

!scope=row|San Juan County

|align=center|63

|San Juan County

!scope=row|Hinsdale County

|align=center|64

|Hinsdale County

|-class=sortbottom style="background-color:#FFFFDD;"

|State of Colorado

|align=center|State

|State of Colorado

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.

{|class="wikitable sortable plainrowheaders"

|+Counties formerly within the area of the State of Colorado

!scope=col|County

!scope=col|Territory or State

!scope=col|Date created

!scope=col|Date superseded

!scope=col|History

!scope=row|Taos County

|Territory of New Mexico

|align=center|Jan 09, 1852

|align=center|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.

!scope=row|Great Salt Lake County

|Territory of Utah

|align=center|Mar 03, 1852

|align=center|Feb 28, 1861

|Created in 1852. Excluded from the new Territory of Colorado in 1861.

!scope=row|Green River County

|Territory of Utah

|align=center|Mar 03, 1852

|align=center|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.

!scope=row|Iron County

|Territory of Utah

|align=center|Mar 03, 1852

|align=center|Feb 28, 1861

|Created in 1852. Excluded from the new Territory of Colorado in 1861.

!scope=row|Sanpete County

|Territory of Utah

|align=center|Mar 03, 1852

|align=center|Feb 28, 1861

|Created in 1852. Excluded from the new Territory of Colorado in 1861.

!scope=row|Utah County

|Territory of Utah

|align=center|Mar 03, 1852

|align=center|Feb 28, 1861

|Created in 1852. Excluded from the new Territory of Colorado in 1861.

!scope=row|Washington County

|Territory of Utah

|align=center|Mar 03, 1852

|align=center|Feb 28, 1861

|Created in 1852. Excluded from the new Territory of Colorado in 1861.

!scope=row|Arapahoe County

|Territory of Kansas

|align=center|Aug 25, 1855

|align=center|Feb 28, 1861

|Created in 1855, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|Beaver County

|Territory of Utah

|align=center|Jan 05, 1856

|align=center|Feb 28, 1861

|Split from Iron and Millard counties in 1856. Excluded from the new Territory of Colorado in 1861.

!scope=row|Broderick County

|Territory of Kansas

|align=center|Feb 07, 1859

|align=center|Jan 29, 1861

|Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|El Paso County

|Territory of Kansas

|align=center|Feb 07, 1859

|align=center|Jan 29, 1861

|Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|Fremont County

|Territory of Kansas

|align=center|Feb 07, 1859

|align=center|Jan 29, 1861

|Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|Montana County

|Territory of Kansas

|align=center|Feb 07, 1859

|align=center|Jan 29, 1861

|Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|Oro County

|Territory of Kansas

|align=center|Feb 07, 1859

|align=center|Jan 29, 1861

|Split from Arapahoe County in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|Peketon County

|Territory of Kansas

|align=center|Feb 07, 1859

|align=center|Jan 29, 1861

|Created in 1859, but never organized. Reverted to unorganized territory when Kansas joined the Union in 1861.

!scope=row|Arrappahoe County

|Territory of Jefferson

|align=center|Nov 28, 1859

|align=center|Feb 28, 1861