RANKING · 2010 CENSUS · 64 SHOWN OF 64

Largest by population, Colorado counties · 2010

The most populous Colorado counties as of the 2010 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, COCO622,263+20%

02Denver County, COCO600,158+8%

03Arapahoe County, COCO572,003+17%

04Jefferson County, COCO534,543+1%

05Adams County, COCO441,603+21%

06Larimer County, COCO299,630+19%

07Boulder County, COCO294,567+1%

08Douglas County, COCO285,465+62%

09Weld County, COCO252,825+40%

10Pueblo County, COCO159,063+12%

11Mesa County, COCO146,723+26%

12Garfield County, COCO56,389+29%

13Broomfield County, COCO55,889–

14Eagle County, COCO52,197+25%

15La Plata County, COCO51,334+17%

16Fremont County, COCO46,824+1%

17Montrose County, COCO41,276+23%

18Delta County, COCO30,952+11%

19Morgan County, COCO28,159+4%

20Summit County, COCO27,994+19%

21Montezuma County, COCO25,535+7%

22Routt County, COCO23,509+19%

23Teller County, COCO23,350+14%

24Elbert County, COCO23,086+16%

25Logan County, COCO22,709+11%

26Otero County, COCO18,831−7%

27Chaffee County, COCO17,809+10%

28Pitkin County, COCO17,148+15%

29Park County, COCO16,206+12%

30Las Animas County, COCO15,507+2%

31Alamosa County, COCO15,445+3%

32Gunnison County, COCO15,324+10%

33Grand County, COCO14,843+19%

34Moffat County, COCO13,795+5%

35Prowers County, COCO12,551−13%

36Archuleta County, COCO12,084+22%

37Rio Grande County, COCO11,982−3%

38Yuma County, COCO10,043+2%

39Clear Creek County, COCO9,088−3%

40Kit Carson County, COCO8,270+3%

41Conejos County, COCO8,256−2%

42San Miguel County, COCO7,359+12%

43Lake County, COCO7,310−6%

44Huerfano County, COCO6,711−15%

45Rio Blanco County, COCO6,666+11%

46Bent County, COCO6,499+8%

47Saguache County, COCO6,108+3%

48Crowley County, COCO5,823+6%

49Lincoln County, COCO5,467−10%

50Gilpin County, COCO5,441+14%

51Washington County, COCO4,814−2%

52Phillips County, COCO4,442−1%

53Ouray County, COCO4,436+19%

54Custer County, COCO4,255+21%

55Baca County, COCO3,788−16%

56Costilla County, COCO3,524−4%

57Sedgwick County, COCO2,379−13%

58Dolores County, COCO2,064+12%

59Cheyenne County, COCO1,836−18%

60Kiowa County, COCO1,398−14%

61Jackson County, COCO1,394−12%

62Hinsdale County, COCO843+7%

63Mineral County, COCO712−14%

64San Juan County, COCO699+25%

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