RANKING · 2025 ESTIMATES · 64 SHOWN OF 64

Most population gained, Colorado counties

Colorado counties that added the most residents from the 2020 census to 2025, 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

01Weld County, COCO378,426+49,445+1%

02Douglas County, COCO399,396+41,418−64%

03Adams County, COCO554,668+35,096−64%

04El Paso County, COCO757,040+26,645−78%

05Denver County, COCO740,613+25,091−71%

06Arapahoe County, COCO673,820+18,750−81%

07Larimer County, COCO377,292+18,226−72%

08Mesa County, COCO162,845+7,142−69%

09Broomfield County, COCO79,174+5,062–

10Elbert County, COCO30,534+4,472−56%

11Montrose County, COCO44,591+1,912−79%

12Garfield County, COCO63,474+1,789−87%

13Chaffee County, COCO20,831+1,355−62%

14La Plata County, COCO56,898+1,260−89%

15Morgan County, COCO30,306+1,195−77%

16Pueblo County, COCO169,277+1,115−94%

17Fremont County, COCO50,039+1,100−92%

18Delta County, COCO32,178+982−86%

19Archuleta County, COCO14,306+947−79%

20Park County, COCO18,314+924−87%

21Custer County, COCO5,590+886−44%

22Montezuma County, COCO26,678+829−84%

23Grand County, COCO16,496+779−83%

24Gunnison County, COCO17,439+521−86%

25Routt County, COCO25,329+500−91%

26Summit County, COCO31,517+462−96%

27Ouray County, COCO5,265+391−73%

28Saguache County, COCO6,732+364−72%

29Alamosa County, COCO16,688+312−77%

30Gilpin County, COCO6,073+265−84%

31Huerfano County, COCO7,011+191−90%

32Costilla County, COCO3,679+180−62%

33Rio Blanco County, COCO6,683+154+1000%

34Dolores County, COCO2,466+140−59%

35Lake County, COCO7,552+116−94%

36San Juan County, COCO813+108−158%

37Conejos County, COCO7,529+68−93%

38Bent County, COCO5,716+66−93%

39Teller County, COCO24,756+46−99%

40Mineral County, COCO910+45−84%

41Kit Carson County, COCO7,069-18−102%

42Lincoln County, COCO5,645-30−102%

43Kiowa County, COCO1,412-34−48%

44Cheyenne County, COCO1,713-35−79%

45Hinsdale County, COCO753-35−111%

46Washington County, COCO4,732-85−175%

47Yuma County, COCO9,896-92−110%

48Phillips County, COCO4,420-110−138%

49Prowers County, COCO11,884-115−110%

50Sedgwick County, COCO2,247-157−375%

51Baca County, COCO3,347-159+308%

52Las Animas County, COCO14,391-164−111%

53Jackson County, COCO1,211-168+500%

54Moffat County, COCO13,122-170−109%

55Crowley County, COCO5,677-245−116%

56San Miguel County, COCO7,753-319−111%

57Clear Creek County, COCO8,994-403−124%

58Rio Grande County, COCO11,087-452−128%

59Pitkin County, COCO16,625-733−133%

60Logan County, COCO20,654-874−130%

61Otero County, COCO17,683-1,007−899%

62Eagle County, COCO54,291-1,440−107%

63Boulder County, COCO328,560-2,198−103%

64Jefferson County, COCO580,451-2,459−103%

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