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. The median across all 64 is +180. Biggest climber in the top 100 since 2020: Conejos County, CO, up 23 places to #37.

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SAME RANKING BYCities States Metros

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01▲4Weld County, COCO378,426+49,445+1%

02▲4Douglas County, COCO399,396+41,418−64%

03▲1Adams County, COCO554,668+35,096−64%

04▼2El Paso County, COCO757,040+26,645−78%

05▼4Denver County, COCO740,613+25,091−71%

06▼3Arapahoe County, COCO673,820+18,750−81%

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

08▲4Mesa County, COCO162,845+7,142−69%

09▲1Broomfield County, COCO79,174+5,062–

10▲7Elbert County, COCO30,534+4,472−56%

11▲10Montrose County, COCO44,591+1,912−79%

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

13▲6Chaffee County, COCO20,831+1,355−62%

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

15▲11Morgan County, COCO30,306+1,195−77%

16▼5Pueblo County, COCO169,277+1,115−94%

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

18▲19Delta County, COCO32,178+982−86%

19▲5Archuleta County, COCO14,306+947−79%

20▲5Park County, COCO18,314+924−87%

21▲9Custer County, COCO5,590+886−44%

22▲11Montezuma County, COCO26,678+829−84%

23▲5Grand County, COCO16,496+779−83%

24▼4Gunnison County, COCO17,439+521−86%

25▼2Routt County, COCO25,329+500−91%

26▼10Summit County, COCO31,517+462−96%

27▲4Ouray County, COCO5,265+391−73%

28▲8Saguache County, COCO6,732+364−72%

29▼2Alamosa County, COCO16,688+312−77%

30▲2Gilpin County, COCO6,073+265−84%

31▲11Huerfano County, COCO7,011+191−90%

32▲18Costilla County, COCO3,679+180−62%

33▲21Rio Blanco County, COCO6,683+154+1000%

34▲1Dolores County, COCO2,466+140−59%

35▲6Lake County, COCO7,552+116−94%

36▲11San Juan County, COCO813+108−158%

37▲23Conejos County, COCO7,529+68−93%

38▲23Bent County, COCO5,716+66−93%

39▼17Teller County, COCO24,756+46−99%

40Mineral County, COCO910+45−84%

41▲23Kit Carson County, COCO7,069-18−102%

42▼3Lincoln County, COCO5,645-30−102%

43▲2Kiowa County, COCO1,412-34−48%

44▲9Cheyenne County, COCO1,713-35−79%

45▲6Hinsdale County, COCO753-35−111%

46▲2Washington County, COCO4,732-85−175%

47▲5Yuma County, COCO9,896-92−110%

48▼4Phillips County, COCO4,420-110−138%

49▲10Prowers County, COCO11,884-115−110%

50▼4Sedgwick County, COCO2,247-157−375%

51▲5Baca County, COCO3,347-159+308%

52▲10Las Animas County, COCO14,391-164−111%

53▼4Jackson County, COCO1,211-168+500%

54▲4Moffat County, COCO13,122-170−109%

55▼12Crowley County, COCO5,677-245−116%

56▼27San Miguel County, COCO7,753-319−111%

57▼23Clear Creek County, COCO8,994-403−124%

58▼1Rio Grande County, COCO11,087-452−128%

59▼21Pitkin County, COCO16,625-733−133%

60▲3Logan County, COCO20,654-874−130%

61▼6Otero County, COCO17,683-1,007−899%

62▼47Eagle County, COCO54,291-1,440−107%

63▼54Boulder County, COCO328,560-2,198−103%

64▼56Jefferson County, COCO580,451-2,459−103%

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU POPULATION ESTIMATES