RANKING · 1990 CENSUS · 63 SHOWN OF 63

Most densely populated, Colorado counties · 1990

Colorado counties ranked by residents per square mile (2023). This list covers the 63 counties in Colorado that qualify, ranked against each other statewide.

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YEAR1990 2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION DENSITYVS 2000

01Denver County, COCO740,6133,055−16%

02Jefferson County, COCO580,451574−17%

03Arapahoe County, COCO673,820491−20%

04Boulder County, COCO328,560310−23%

05Adams County, COCO554,668227−27%

06El Paso County, COCO757,040187−23%

07Douglas County, COCO399,39672−66%

08Larimer County, COCO377,29272−26%

09Pueblo County, COCO169,27752−13%

10Weld County, COCO378,42633−27%

11Mesa County, COCO162,84528−20%

12Teller County, COCO24,75622−39%

13Summit County, COCO31,51721−45%

14Fremont County, COCO50,03921−30%

15Gilpin County, COCO6,07320−35%

16Clear Creek County, COCO8,99419−18%

17La Plata County, COCO56,89819−27%

18Alamosa County, COCO16,68819−9%

19Delta County, COCO32,17818−25%

20Morgan County, COCO30,30617−19%

21Otero County, COCO17,68316−1%

22Lake County, COCO7,55216−23%

23Pitkin County, COCO16,62513−15%

24Eagle County, COCO54,29113−47%

25Chaffee County, COCO20,83113−22%

26Rio Grande County, COCO11,08712−13%

27Montrose County, COCO44,59111−27%

28Garfield County, COCO63,47410−32%

29Logan County, COCO20,65410−14%

30Montezuma County, COCO26,6789−22%

31Prowers County, COCO11,8848−8%

32Phillips County, COCO4,4206−6%

33Routt County, COCO25,3296−28%

34Conejos County, COCO7,5296−11%

35Elbert County, COCO30,5345−51%

36Crowley County, COCO5,6775−28%

37Sedgwick County, COCO2,2475−2%

38Grand County, COCO16,4964−36%

39Ouray County, COCO5,2654−39%

40Archuleta County, COCO14,3064−46%

41Yuma County, COCO9,8964−9%

42Huerfano County, COCO7,0114−24%

43Bent County, COCO5,7163−16%

44Kit Carson County, COCO7,0693−11%

45Park County, COCO18,3143−51%

46Gunnison County, COCO17,4393−26%

47Las Animas County, COCO14,3913−9%

48San Miguel County, COCO7,7533−45%

49Custer County, COCO5,5903−45%

50Costilla County, COCO3,6793−13%

51Moffat County, COCO13,1222−14%

52San Juan County, COCO8132+34%

53Washington County, COCO4,7322−2%

54Rio Blanco County, COCO6,6832−0%

55Baca County, COCO3,3472+1%

56Lincoln County, COCO5,6452−26%

57Saguache County, COCO6,7321−22%

58Dolores County, COCO2,4661−18%

59Cheyenne County, COCO1,7131+7%

60Jackson County, COCO1,2111+2%

61Kiowa County, COCO1,4121+4%

62Mineral County, COCO9101−33%

63Hinsdale County, COCO7530−41%

SHOWING 1–63 OF 63

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UPDATED 2026-06-02 · DATA: US CENSUS BUREAU ACS 5-YEAR ESTIMATES