Named for thecottonwood treeswhich grow along theRio Grandeand its tributaries.Alamosais a Spanish word for acottonwood grove.
15,445
723.21sqmi (1,873km)
Arapahoe County
005
Littleton
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado. Renamed South Arapahoe County for the five months from November 15, 1902 to April 11, 1903.
Named for predecessorArapahoe County, Kansas Territory, which in turn was named for theArapaho NationofNative Americans.
572,003
804.41sqmi (2,083km)
Archuleta County
007
Pagosa Springs
1885-04-14
Split fromConejos County.
Named in honor ofColorado State SenatorAntonio D. Archuleta.
12,084
1,354.53sqmi (3,508km)
Baca County
009
Springfield
1889-04-16
Split fromLas Animas County.
Named in honor of pioneer andColorado territorial legislatorFelipe Baca.
3,788
2,558.48sqmi (6,626km)
Bent County
011
Las Animas
1870-02-11
Split fromHuerfano Countyand former Cheyenne and Arapaho tribal land.
Named in honor of frontier traderWilliam Bent.
6,499
1,541.07sqmi (3,991km)
Boulder County
013
Boulder
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named for the abundance ofgranitebouldersalongBoulder Creek.
294,567
740.48sqmi (1,918km)
City and County of Broomfield
014
Broomfield
2001-11-15
Split fromBoulder,Adams,Jefferson, andWeldcounties and reorganized as aconsolidated city and county.
Named for thebroom cornthat was formerly grown in the area.
55,889
33.57sqmi (87km)
Chaffee County
015
Salida
1879-02-10
Split fromCarbonate County.
Named in honor ofJerome Bunty Chaffee, one ofColorado's first twoU.S. Senatorsfrom 1876 to 1879.
17,809
1,014.12sqmi (2,627km)
Cheyenne County
017
Cheyenne Wells
1889-03-25
Split fromElbertandBentcounties.
Named for theCheyenne NationofNative Americans.
1,836
1,781.90sqmi (4,615km)
Clear Creek County
019
Georgetown
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named forClear Creekwhich originates in the county.
9,088
396.53sqmi (1,027km)
Conejos County
021
Conejos
1861-11-01
Guadalupe County, one of the 17 original counties of theTerritory of Colorado, was renamedConejos Countyafter six days on November 7, 1861.
Named for thecottontail rabbitsin the area.Conejosis a Spanish word forrabbits.
8,256
1,290.22sqmi (3,342km)
Costilla County
023
San Luis
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named for the Costilla River.Costillais a Spanish word meaning eitherlittle riborfurring timber.
3,524
1,229.38sqmi (3,184km)
Crowley County
025
Ordway
1911-05-29
Split fromOtero County.
Named in honor ofColorado State SenatorJohn H. Crowley.
5,823
800.27sqmi (2,073km)
Custer County
027
Westcliffe
1877-03-09
Split fromFremont County.
Named in memory ofGeorge Armstrong Custer, (1839 - 1876), the U.S. Armycoloneldefeated and killed at theBattle of the Little Bighorn.
4,255
739.24sqmi (1,915km)
Delta County
029
Delta
1883-02-11
Split fromGunnison County.
Named for the town ofDeltalocated at thedeltaof theUncompahgre River.
30,952
1,149.44sqmi (2,977km)
City and County of Denver
031
Denver
1902-11-15
The originalArapahoeCounty Seatwas split fromArapahoe Countyand reorganized as aconsolidated city and county.
Named to curry favor withJames W. Denver,Governorof theTerritory of Kansasfrom 1857 to 1859.
600,158
155.66sqmi (403km)
Dolores County
033
Dove Creek
1881-03-04
Split fromOuray County.
Named for theDolores River, which was originally namedel Rio de Nuestra Senora de los Dolores, which is Spanish forthe River of our Lady of Sorrows.
2,064
1,076.93sqmi (2,789km)
Douglas County
035
Castle Rock
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named in honor ofStephen Arnold Douglas, (1813 - 1861),U.S. SenatorfromIllinoisfrom 1847 to 1861.
285,465
842.30sqmi (2,182km)
Eagle County
037
Eagle
1883-02-11
Split fromSummit County.
Named for theEagle Riverwhich originates in the county.
52,197
1,700.76sqmi (4,405km)
El Paso County
041
Colorado Springs
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named forUte Passin the county.El pasois a Spanish expression forthe pass.
622,263
2,128.60sqmi (5,513km)
Elbert County
039
Kiowa
1874-02-02
Split fromDouglas County.
Named in honor ofSamuel Hitt Elbert, the sixthGovernorof theTerritory of Colorado.
23,086
1,849.08sqmi (4,789km)
Fremont County
043
Cañon City
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named in honor ofJohn Charles Frémont(1813 - 1890), the explorer, U.S. Army general, andU.S. SenatorfromCalifornia.
46,824
1,533.09sqmi (3,971km)
Garfield County
045
Glenwood Springs
1883-02-10
Split fromSummit County.
Named in honor ofJames Abram Garfield(1831 - 1881), the twentiethPresident of the United States.
56,389
2,958.23sqmi (7,662km)
Gilpin County
047
Central City
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named in honor ofWilliam Gilpin, the firstGovernorof theTerritory of Colorado.
5,441
150.15sqmi (389km)
Grand County
049
Hot Sulphur Springs
1874-02-02
Split fromSummit County.
Named for theGrand Riverwhich originates in the county. The Grand River was renamed theColorado Riverin 1921, but the county retains the original name.
14,843
1,868.53sqmi (4,839km)
Gunnison County
051
Gunnison
1877-03-09
Split fromLake County.
Named in honor ofJohn Williams Gunnison, the U.S. Army captain who explored the region.
15,324
3,259.22sqmi (8,441km)
Hinsdale County
053
Lake City
1874-02-10
Split fromLake,Conejos, andCostillacounties.
Named in honor of George Aaron Hinsdale, a Lieutenant Governor of theTerritory of Colorado.
843
1,123.35sqmi (2,909km)
Huerfano County
055
Walsenburg
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named forHuerfano Butte, a solitary volcanic plug.Huerfanois a Spanish word meaningorphan.
6,711
1,592.37sqmi (4,124km)
Jackson County
057
Walden
1909-05-05
Split fromLarimer County.
Named in honor ofAndrew Jackson(1767 - 1845), the seventhPresident of the United States.
1,394
1,619.75sqmi (4,195km)
Jefferson County
059
Golden
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named for its extralegal predecessor county,Jefferson County, Jefferson Territory, which in turn was named in honor ofThomas Jefferson(1743 - 1826), the author of theDeclaration of Independenceand the thirdPresident of the United States.
534,543
772.85sqmi (2,002km)
Kiowa County
061
Eads
1889-04-11
Split fromBent County.
Named for theKiowa NationofNative Americans.
1,398
1,785.90sqmi (4,625km)
Kit Carson County
063
Burlington
1889-04-11
Split fromElbert County.
Named in honor ofChristopher Houston "Kit" Carson, the famous frontier scout and soldier.
8,270
2,162.43sqmi (5,601km)
La Plata County
067
Durango
1874-02-10
Split fromLakeandConejoscounties.
Named for the manysilverdeposits in the area.La platais a Spanish expression forthe silver.
51,334
1,700.44sqmi (4,404km)
Lake County
065
Leadville
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado. RenamedCarbonate Countyfor the two days from February 8–10, 1879.
Named for theTwin Lakesin the county.
7,310
383.55sqmi (993km)
Larimer County
069
Fort Collins
1861-11-01
Created as one of the 17 original counties of theTerritory of Colorado.
Named in honor ofWilliam Larimer, a pioneer entrepreneur.
299,630
2,631.75sqmi (6,816km)
Las Animas County
071
Trinidad
1866-02-09
Split fromHuerfano County.
Named for theAnimas River, which was originally namedel Rio de las Animas Perdidas, which is Spanish forthe River of the Souls in Purgatory.
15,507
4,773.27sqmi (12,363km)
Lincoln County
073
Hugo
1889-04-11
Split fromElbertandBentcounties.
Named in honor ofAbraham Lincoln(1809 - 1865), the sixteenthPresident of the United States.
5,467
2,585.21sqmi (6,696km)
Logan County
075
Sterling
1887-02-25
Split fromWeld County.
Named in honor ofJohn Alexander Logan(1826 - 1886), a U.S. Army general andU.S. SenatorfromIllinois.
22,709
1,845.31sqmi (4,779km)
Mesa County
077
Grand Junction
1883-02-14
Split fromGunnison County.
Named for themesaformations which are widespread through the area.