RANKING · 2025 ESTIMATES · 64 SHOWN OF 64

Most population lost, Colorado counties

Colorado counties that lost 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

01Jefferson County, COCO580,451-2,459−103%

02Boulder County, COCO328,560-2,198−103%

03Eagle County, COCO54,291-1,440−107%

04Otero County, COCO17,683-1,007−899%

05Logan County, COCO20,654-874−130%

06Pitkin County, COCO16,625-733−133%

07Rio Grande County, COCO11,087-452−128%

08Clear Creek County, COCO8,994-403−124%

09San Miguel County, COCO7,753-319−111%

10Crowley County, COCO5,677-245−116%

11Moffat County, COCO13,122-170−109%

12Jackson County, COCO1,211-168+500%

13Las Animas County, COCO14,391-164−111%

14Baca County, COCO3,347-159+308%

15Sedgwick County, COCO2,247-157−375%

16Prowers County, COCO11,884-115−110%

17Phillips County, COCO4,420-110−138%

18Yuma County, COCO9,896-92−110%

19Washington County, COCO4,732-85−175%

20Cheyenne County, COCO1,713-35−79%

21Hinsdale County, COCO753-35−111%

22Kiowa County, COCO1,412-34−48%

23Lincoln County, COCO5,645-30−102%

24Kit Carson County, COCO7,069-18−102%

25Mineral County, COCO910+45−84%

26Teller County, COCO24,756+46−99%

27Bent County, COCO5,716+66−93%

28Conejos County, COCO7,529+68−93%

29San Juan County, COCO813+108−158%

30Lake County, COCO7,552+116−94%

31Dolores County, COCO2,466+140−59%

32Rio Blanco County, COCO6,683+154+1000%

33Costilla County, COCO3,679+180−62%

34Huerfano County, COCO7,011+191−90%

35Gilpin County, COCO6,073+265−84%

36Alamosa County, COCO16,688+312−77%

37Saguache County, COCO6,732+364−72%

38Ouray County, COCO5,265+391−73%

39Summit County, COCO31,517+462−96%

40Routt County, COCO25,329+500−91%

41Gunnison County, COCO17,439+521−86%

42Grand County, COCO16,496+779−83%

43Montezuma County, COCO26,678+829−84%

44Custer County, COCO5,590+886−44%

45Park County, COCO18,314+924−87%

46Archuleta County, COCO14,306+947−79%

47Delta County, COCO32,178+982−86%

48Fremont County, COCO50,039+1,100−92%

49Pueblo County, COCO169,277+1,115−94%

50Morgan County, COCO30,306+1,195−77%

51La Plata County, COCO56,898+1,260−89%

52Chaffee County, COCO20,831+1,355−62%

53Garfield County, COCO63,474+1,789−87%

54Montrose County, COCO44,591+1,912−79%

55Elbert County, COCO30,534+4,472−56%

56Broomfield County, COCO79,174+5,062–

57Mesa County, COCO162,845+7,142−69%

58Larimer County, COCO377,292+18,226−72%

59Arapahoe County, COCO673,820+18,750−81%

60Denver County, COCO740,613+25,091−71%

61El Paso County, COCO757,040+26,645−78%

62Adams County, COCO554,668+35,096−64%

63Douglas County, COCO399,396+41,418−64%

64Weld County, COCO378,426+49,445+1%

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