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. The median across all 64 is +180. Biggest climber in the top 100 since 2020: Jefferson County, CO, up 56 places to #1.

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SAME RANKING BYCities States Metros

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01▲56Jefferson County, COCO580,451-2,459−103%

02▲54Boulder County, COCO328,560-2,198−103%

03▲47Eagle County, COCO54,291-1,440−107%

04▲6Otero County, COCO17,683-1,007−899%

05▼3Logan County, COCO20,654-874−130%

06▲21Pitkin County, COCO16,625-733−133%

07▲1Rio Grande County, COCO11,087-452−128%

08▲23Clear Creek County, COCO8,994-403−124%

09▲27San Miguel County, COCO7,753-319−111%

10▲12Crowley County, COCO5,677-245−116%

11▼4Moffat County, COCO13,122-170−109%

12▲4Jackson County, COCO1,211-168+500%

13▼10Las Animas County, COCO14,391-164−111%

14▼5Baca County, COCO3,347-159+308%

15▲4Sedgwick County, COCO2,247-157−375%

16▼10Prowers County, COCO11,884-115−110%

17▲4Phillips County, COCO4,420-110−138%

18▼4Yuma County, COCO9,896-92−110%

19▼2Washington County, COCO4,732-85−175%

20▼8Cheyenne County, COCO1,713-35−79%

21▼8Hinsdale County, COCO753-35−111%

22▼2Kiowa County, COCO1,412-34−48%

23▲3Lincoln County, COCO5,645-30−102%

24▼23Kit Carson County, COCO7,069-18−102%

25Mineral County, COCO910+45−84%

26▲17Teller County, COCO24,756+46−99%

27▼23Bent County, COCO5,716+66−93%

28▼23Conejos County, COCO7,529+68−93%

29▼11San Juan County, COCO813+108−158%

30▼6Lake County, COCO7,552+116−94%

31▼1Dolores County, COCO2,466+140−59%

32▼21Rio Blanco County, COCO6,683+154+1000%

33▼18Costilla County, COCO3,679+180−62%

34▼11Huerfano County, COCO7,011+191−90%

35▼2Gilpin County, COCO6,073+265−84%

36▲2Alamosa County, COCO16,688+312−77%

37▼8Saguache County, COCO6,732+364−72%

38▼4Ouray County, COCO5,265+391−73%

39▲10Summit County, COCO31,517+462−96%

40▲2Routt County, COCO25,329+500−91%

41▲4Gunnison County, COCO17,439+521−86%

42▼5Grand County, COCO16,496+779−83%

43▼11Montezuma County, COCO26,678+829−84%

44▼9Custer County, COCO5,590+886−44%

45▼5Park County, COCO18,314+924−87%

46▼5Archuleta County, COCO14,306+947−79%

47▼19Delta County, COCO32,178+982−86%

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

49▲5Pueblo County, COCO169,277+1,115−94%

50▼11Morgan County, COCO30,306+1,195−77%

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

52▼6Chaffee County, COCO20,831+1,355−62%

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

54▼10Montrose County, COCO44,591+1,912−79%

55▼7Elbert County, COCO30,534+4,472−56%

56▼1Broomfield County, COCO79,174+5,062–

57▼4Mesa County, COCO162,845+7,142−69%

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

59▲3Arapahoe County, COCO673,820+18,750−81%

60▲4Denver County, COCO740,613+25,091−71%

61▲2El Paso County, COCO757,040+26,645−78%

62▼1Adams County, COCO554,668+35,096−64%

63▼4Douglas County, COCO399,396+41,418−64%

64▼4Weld County, COCO378,426+49,445+1%

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