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.

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SAME RANKING BYCities States Metros

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

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

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

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

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

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

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

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

08Lake County, MTMT33,392+2,258−59%

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

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

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

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

13Park County, MTMT18,214+1,023−10%

14Carbon County, MTMT11,466+993−33%

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

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

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

18Mineral County, MTMT5,185+650+14%

19Cascade County, MTMT85,029+615−77%

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

21Fergus County, MTMT11,825+379−299%

22Granite County, MTMT3,658+349+24%

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

24Teton County, MTMT6,496+270+55%

25Toole County, MTMT5,211+240+9%

26Powell County, MTMT7,157+211−62%

27Meagher County, MTMT2,137+210+86%

28Pondera County, MTMT6,072+174−2033%

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

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

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

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

33Petroleum County, MTMT548+52−300%

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

35Prairie County, MTMT1,112+24−113%

36Golden Valley County, MTMT844+21−84%

37Liberty County, MTMT1,957-2−99%

38McCone County, MTMT1,720-9−97%

39Phillips County, MTMT4,203-14−98%

40Garfield County, MTMT1,148-25−92%

41Chouteau County, MTMT5,865-30−106%

42Carter County, MTMT1,383-32−78%

43Treasure County, MTMT728-34+162%

44Daniels County, MTMT1,612-49−80%

45Wibaux County, MTMT885-52−58%

46Rosebud County, MTMT8,253-76−93%

47Fallon County, MTMT2,959-90−66%

48Sheridan County, MTMT3,436-103−84%

49Richland County, MTMT11,377-114−89%

50Hill County, MTMT16,167-142−86%

51Blaine County, MTMT6,860-184−165%

52Valley County, MTMT7,385-193−66%

53Dawson County, MTMT8,692-248−44%

54Glacier County, MTMT13,463-315−128%

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

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

SHOWING 1–56 OF 56

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