RANKING · 2025 ESTIMATES · 64 SHOWN OF 64

Largest by population, Colorado counties

The most populous Colorado counties as of the 2025 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, COCO757,040+46%

02Denver County, COCO740,613+34%

03Arapahoe County, COCO673,820+38%

04Jefferson County, COCO580,451+10%

05Adams County, COCO554,668+52%

06Douglas County, COCO399,396+127%

07Weld County, COCO378,426+109%

08Larimer County, COCO377,292+50%

09Boulder County, COCO328,560+13%

10Pueblo County, COCO169,277+20%

11Mesa County, COCO162,845+40%

12Broomfield County, COCO79,174–

13Garfield County, COCO63,474+45%

14La Plata County, COCO56,898+29%

15Eagle County, COCO54,291+30%

16Fremont County, COCO50,039+8%

17Montrose County, COCO44,591+33%

18Delta County, COCO32,178+16%

19Summit County, COCO31,517+34%

20Elbert County, COCO30,534+54%

21Morgan County, COCO30,306+12%

22Montezuma County, COCO26,678+12%

23Routt County, COCO25,329+29%

24Teller County, COCO24,756+20%

25Chaffee County, COCO20,831+28%

26Logan County, COCO20,654+1%

27Park County, COCO18,314+26%

28Otero County, COCO17,683−13%

29Gunnison County, COCO17,439+25%

30Alamosa County, COCO16,688+12%

31Pitkin County, COCO16,625+12%

32Grand County, COCO16,496+33%

33Las Animas County, COCO14,391−5%

34Archuleta County, COCO14,306+45%

35Moffat County, COCO13,122−0%

36Prowers County, COCO11,884−18%

37Rio Grande County, COCO11,087−11%

38Yuma County, COCO9,896+1%

39Clear Creek County, COCO8,994−4%

40San Miguel County, COCO7,753+18%

41Lake County, COCO7,552−3%

42Conejos County, COCO7,529−10%

43Kit Carson County, COCO7,069−12%

44Huerfano County, COCO7,011−11%

45Saguache County, COCO6,732+14%

46Rio Blanco County, COCO6,683+12%

47Gilpin County, COCO6,073+28%

48Bent County, COCO5,716−5%

49Crowley County, COCO5,677+3%

50Lincoln County, COCO5,645−7%

51Custer County, COCO5,590+60%

52Ouray County, COCO5,265+41%

53Washington County, COCO4,732−4%

54Phillips County, COCO4,420−1%

55Costilla County, COCO3,679+0%

56Baca County, COCO3,347−26%

57Dolores County, COCO2,466+34%

58Sedgwick County, COCO2,247−18%

59Cheyenne County, COCO1,713−23%

60Kiowa County, COCO1,412−13%

61Jackson County, COCO1,211−23%

62Mineral County, COCO910+10%

63San Juan County, COCO813+46%

64Hinsdale County, COCO753−5%

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UPDATED 2026-07-15 · DATA: US CENSUS BUREAU POPULATION ESTIMATES