RANKING · 2025 ESTIMATES · 56 SHOWN OF 56

Most population lost, Montana counties

Montana counties that lost the most residents from the 2020 census to 2025, by raw count of people rather than percentage. This list covers the 56 counties in Montana that qualify, ranked against each other statewide. The median across all 56 is +174. Biggest climber in the top 100 since 2020: Richland County, MT, up 40 places to #8.

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SAME RANKING BYCities States Metros

RELATEDLargest by population Fastest growing Fastest shrinking Most population gained Most densely populated Most sparsely populated

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01▲37Roosevelt County, MTMT10,242-552+46%

02▲34Big Horn County, MTMT12,752-372−128%

03▲36Glacier County, MTMT13,463-315−128%

04▲13Dawson County, MTMT8,692-248−44%

05▲27Valley County, MTMT7,385-193−66%

06▲35Blaine County, MTMT6,860-184−165%

07▲26Hill County, MTMT16,167-142−86%

08▲40Richland County, MTMT11,377-114−89%

09▲19Sheridan County, MTMT3,436-103−84%

10▲19Fallon County, MTMT2,959-90−66%

11▼10Rosebud County, MTMT8,253-76−93%

12▼1Wibaux County, MTMT885-52−58%

13▼4Daniels County, MTMT1,612-49−80%

14▲9Treasure County, MTMT728-34+162%

15▲20Carter County, MTMT1,383-32−78%

16▲8Chouteau County, MTMT5,865-30−106%

17▼1Garfield County, MTMT1,148-25−92%

18▼3Phillips County, MTMT4,203-14−98%

19McCone County, MTMT1,720-9−97%

20▼18Liberty County, MTMT1,957-2−99%

21▼9Golden Valley County, MTMT844+21−84%

22▼14Prairie County, MTMT1,112+24−113%

23▼16Wheatland County, MTMT2,100+31+138%

24▼4Petroleum County, MTMT548+52−300%

25▼4Sweet Grass County, MTMT3,762+84−82%

26▼13Powder River County, MTMT1,781+87−138%

27▼13Judith Basin County, MTMT2,162+139+196%

28▲2Custer County, MTMT12,034+167−16800%

29▼25Pondera County, MTMT6,072+174−2033%

30▼8Meagher County, MTMT2,137+210+86%

31▼21Powell County, MTMT7,157+211−62%

32▼29Toole County, MTMT5,211+240+9%

33▼6Teton County, MTMT6,496+270+55%

34▼9Deer Lodge County, MTMT9,709+288−133%

35▼1Granite County, MTMT3,658+349+24%

36▼30Fergus County, MTMT11,825+379−299%

37▼32Stillwater County, MTMT9,445+482−71%

38▲12Cascade County, MTMT85,029+615−77%

39▼2Mineral County, MTMT5,185+650+14%

40▼14Beaverhead County, MTMT10,043+672−14%

41▼10Musselshell County, MTMT5,582+852+118%

42▲2Silver Bow County, MTMT36,118+985+48%

43▼3Carbon County, MTMT11,466+993−33%

44▲3Park County, MTMT18,214+1,023−10%

45▼3Jefferson County, MTMT13,329+1,244−41%

46▼3Madison County, MTMT10,026+1,403+63%

47▼2Sanders County, MTMT14,062+1,662+7%

48▼2Broadwater County, MTMT8,493+1,719+61%

49Lake County, MTMT33,392+2,258−59%

50▼32Lincoln County, MTMT22,328+2,651+96%

51▲1Lewis and Clark County, MTMT75,331+4,358−47%

52▼1Ravalli County, MTMT48,582+4,408−60%

53Missoula County, MTMT123,513+5,591−67%

54▲1Yellowstone County, MTMT172,692+7,961−50%

55▲1Gallatin County, MTMT128,740+9,780−44%

56▼2Flathead County, MTMT115,429+11,072−27%

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