RANKING · 2025 ESTIMATES · 56 SHOWN OF 56

Most population gained, Montana counties

Montana counties that added 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: Lincoln County, MT, up 32 places to #7.

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SAME RANKING BYCities States Metros

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

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01▲2Flathead County, MTMT115,429+11,072−27%

02▼1Gallatin County, MTMT128,740+9,780−44%

03▼1Yellowstone County, MTMT172,692+7,961−50%

04Missoula County, MTMT123,513+5,591−67%

05▲1Ravalli County, MTMT48,582+4,408−60%

06▼1Lewis and Clark County, MTMT75,331+4,358−47%

07▲32Lincoln County, MTMT22,328+2,651+96%

08Lake County, MTMT33,392+2,258−59%

09▲2Broadwater County, MTMT8,493+1,719+61%

10▲2Sanders County, MTMT14,062+1,662+7%

11▲3Madison County, MTMT10,026+1,403+63%

12▲3Jefferson County, MTMT13,329+1,244−41%

13▼3Park County, MTMT18,214+1,023−10%

14▲3Carbon County, MTMT11,466+993−33%

15▼2Silver Bow County, MTMT36,118+985+48%

16▲10Musselshell County, MTMT5,582+852+118%

17▲14Beaverhead County, MTMT10,043+672−14%

18▲2Mineral County, MTMT5,185+650+14%

19▼12Cascade County, MTMT85,029+615−77%

20▲32Stillwater County, MTMT9,445+482−71%

21▲30Fergus County, MTMT11,825+379−299%

22▲1Granite County, MTMT3,658+349+24%

23▲9Deer Lodge County, MTMT9,709+288−133%

24▲6Teton County, MTMT6,496+270+55%

25▲29Toole County, MTMT5,211+240+9%

26▲21Powell County, MTMT7,157+211−62%

27▲8Meagher County, MTMT2,137+210+86%

28▲25Pondera County, MTMT6,072+174−2033%

29▼2Custer County, MTMT12,034+167−16800%

30▲14Judith Basin County, MTMT2,162+139+196%

31▲12Powder River County, MTMT1,781+87−138%

32▲4Sweet Grass County, MTMT3,762+84−82%

33▲4Petroleum County, MTMT548+52−300%

34▲16Wheatland County, MTMT2,100+31+138%

35▲14Prairie County, MTMT1,112+24−113%

36▲9Golden Valley County, MTMT844+21−84%

37▲18Liberty County, MTMT1,957-2−99%

38McCone County, MTMT1,720-9−97%

39▲3Phillips County, MTMT4,203-14−98%

40▲1Garfield County, MTMT1,148-25−92%

41▼8Chouteau County, MTMT5,865-30−106%

42▼20Carter County, MTMT1,383-32−78%

43▼9Treasure County, MTMT728-34+162%

44▲4Daniels County, MTMT1,612-49−80%

45▲1Wibaux County, MTMT885-52−58%

46▲10Rosebud County, MTMT8,253-76−93%

47▼19Fallon County, MTMT2,959-90−66%

48▼19Sheridan County, MTMT3,436-103−84%

49▼40Richland County, MTMT11,377-114−89%

50▼26Hill County, MTMT16,167-142−86%

51▼35Blaine County, MTMT6,860-184−165%

52▼27Valley County, MTMT7,385-193−66%

53▼13Dawson County, MTMT8,692-248−44%

54▼36Glacier County, MTMT13,463-315−128%

55▼34Big Horn County, MTMT12,752-372−128%

56▼37Roosevelt County, MTMT10,242-552+46%

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