RANKING · 2020 CENSUS · 64 SHOWN OF 64

Most population gained, Colorado counties · 2020

Colorado counties that added the most residents from the 2010 census to 2020, by raw count of people rather than percentage. This list covers the 64 counties in Colorado that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01Denver County, COCO740,613+115,364+33%

02El Paso County, COCO757,040+108,132−10%

03Arapahoe County, COCO673,820+83,067−14%

04Adams County, COCO554,668+77,969−21%

05Weld County, COCO378,426+76,156+55%

06Douglas County, COCO399,396+72,513−37%

07Larimer County, COCO377,292+59,436−9%

08Jefferson County, COCO580,451+48,367−45%

09Boulder County, COCO328,560+36,191−45%

10Broomfield County, COCO79,174+18,223–

11Pueblo County, COCO169,277+9,099−51%

12Mesa County, COCO162,845+8,980−61%

13Garfield County, COCO63,474+5,296−62%

14La Plata County, COCO56,898+4,304−63%

15Eagle County, COCO54,291+3,534−82%

16Summit County, COCO31,517+3,061−71%

17Elbert County, COCO30,534+2,976−71%

18Fremont County, COCO50,039+2,115−85%

19Chaffee County, COCO20,831+1,667−53%

20Gunnison County, COCO17,439+1,594−57%

21Montrose County, COCO44,591+1,403−84%

22Teller County, COCO24,756+1,360−83%

23Routt County, COCO25,329+1,320−76%

24Archuleta County, COCO14,306+1,275−72%

25Park County, COCO18,314+1,184−84%

26Morgan County, COCO30,306+952−82%

27Alamosa County, COCO16,688+931−31%

28Grand County, COCO16,496+874−80%

29San Miguel County, COCO7,753+713−76%

30Custer County, COCO5,590+449−72%

31Ouray County, COCO5,265+438−70%

32Gilpin County, COCO6,073+367−78%

33Montezuma County, COCO26,678+314−94%

34Clear Creek County, COCO8,994+309−82%

35Dolores County, COCO2,466+262−23%

36Saguache County, COCO6,732+260−80%

37Delta County, COCO32,178+244−96%

38Pitkin County, COCO16,625+210−91%

39Lincoln County, COCO5,645+208−87%

40Mineral County, COCO910+153−44%

41Lake County, COCO7,552+126−93%

42Huerfano County, COCO7,011+109−94%

43Crowley County, COCO5,677+99−94%

44Phillips County, COCO4,420+88−70%

45Kiowa County, COCO1,412+48−173%

46Sedgwick County, COCO2,247+25−56%

47San Juan County, COCO813+6−103%

48Washington County, COCO4,732+3−97%

49Jackson County, COCO1,211-15−46%

50Costilla County, COCO3,679-25−105%

51Hinsdale County, COCO753-55−117%

52Yuma County, COCO9,896-55−106%

53Cheyenne County, COCO1,713-88−47%

54Rio Blanco County, COCO6,683-137−1079%

55Otero County, COCO17,683-141−212%

56Baca County, COCO3,347-282+623%

57Rio Grande County, COCO11,087-443−127%

58Moffat County, COCO13,122-503−128%

59Prowers County, COCO11,884-552−149%

60Conejos County, COCO7,529-795−184%

61Bent County, COCO5,716-849−189%

62Las Animas County, COCO14,391-952−166%

63Logan County, COCO20,654-1,181−140%

64Kit Carson County, COCO7,069-1,183−236%

SHOWING 1–64 OF 64

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