RANKING · 2020 CENSUS · 64 SHOWN OF 64

Largest by population, Colorado counties · 2020

The most populous Colorado counties as of the 2020 population estimates. This list covers the 64 counties in Colorado that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDFastest growing Fastest shrinking Most population gained Most population lost Most densely populated Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATETOTAL POPULATIONVS 2000

01El Paso County, COCO730,395+41%

02Denver County, COCO715,522+29%

03Arapahoe County, COCO655,070+34%

04Jefferson County, COCO582,910+11%

05Adams County, COCO519,572+43%

06Larimer County, COCO359,066+43%

07Douglas County, COCO357,978+104%

08Boulder County, COCO330,758+14%

09Weld County, COCO328,981+82%

10Pueblo County, COCO168,162+19%

11Mesa County, COCO155,703+34%

12Broomfield County, COCO74,112–

13Garfield County, COCO61,685+41%

14Eagle County, COCO55,731+34%

15La Plata County, COCO55,638+27%

16Fremont County, COCO48,939+6%

17Montrose County, COCO42,679+28%

18Delta County, COCO31,196+12%

19Summit County, COCO31,055+32%

20Morgan County, COCO29,111+7%

21Elbert County, COCO26,062+31%

22Montezuma County, COCO25,849+8%

23Routt County, COCO24,829+26%

24Teller County, COCO24,710+20%

25Logan County, COCO21,528+5%

26Chaffee County, COCO19,476+20%

27Otero County, COCO18,690−8%

28Park County, COCO17,390+20%

29Pitkin County, COCO17,358+17%

30Gunnison County, COCO16,918+21%

31Alamosa County, COCO16,376+9%

32Grand County, COCO15,717+26%

33Las Animas County, COCO14,555−4%

34Archuleta County, COCO13,359+35%

35Moffat County, COCO13,292+1%

36Prowers County, COCO11,999−17%

37Rio Grande County, COCO11,539−7%

38Yuma County, COCO9,988+1%

39Clear Creek County, COCO9,397+1%

40San Miguel County, COCO8,072+22%

41Conejos County, COCO7,461−11%

42Lake County, COCO7,436−5%

43Kit Carson County, COCO7,087−12%

44Huerfano County, COCO6,820−13%

45Rio Blanco County, COCO6,529+9%

46Saguache County, COCO6,368+8%

47Crowley County, COCO5,922+7%

48Gilpin County, COCO5,808+22%

49Lincoln County, COCO5,675−7%

50Bent County, COCO5,650−6%

51Ouray County, COCO4,874+30%

52Washington County, COCO4,817−2%

53Custer County, COCO4,704+34%

54Phillips County, COCO4,530+1%

55Baca County, COCO3,506−22%

56Costilla County, COCO3,499−4%

57Sedgwick County, COCO2,404−12%

58Dolores County, COCO2,326+26%

59Cheyenne County, COCO1,748−22%

60Kiowa County, COCO1,446−11%

61Jackson County, COCO1,379−13%

62Mineral County, COCO865+4%

63Hinsdale County, COCO788−0%

64San Juan County, COCO705+26%

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UPDATED 2026-07-15 · DATA: US CENSUS BUREAU DECENNIAL CENSUS