RANKING · 2020 CENSUS · 56 SHOWN OF 56

Most population gained, Montana counties · 2020

Montana counties that added the most residents from the 2010 census to 2020, 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

01Gallatin County, MTMT128,740+29,447+70%

02Yellowstone County, MTMT172,692+16,759+5%

03Flathead County, MTMT115,429+13,429−12%

04Missoula County, MTMT123,513+8,623−50%

05Lewis and Clark County, MTMT75,331+7,578−8%

06Ravalli County, MTMT48,582+3,962−64%

07Cascade County, MTMT85,029+3,087+16%

08Lake County, MTMT33,392+2,388−56%

09Richland County, MTMT11,377+1,745−266%

10Park County, MTMT18,214+1,555+37%

11Broadwater County, MTMT8,493+1,162+9%

12Sanders County, MTMT14,062+987−37%

13Silver Bow County, MTMT36,118+933+40%

14Madison County, MTMT10,026+932+8%

15Jefferson County, MTMT13,329+679−68%

16Blaine County, MTMT6,860+553+97%

17Carbon County, MTMT11,466+395−73%

18Glacier County, MTMT13,463+379−66%

19Roosevelt County, MTMT10,242+369−197%

20Mineral County, MTMT5,185+312−45%

21Big Horn County, MTMT12,752+259−81%

22Carter County, MTMT1,383+255−278%

23Granite County, MTMT3,658+230−18%

24Hill County, MTMT16,167+213−122%

25Valley County, MTMT7,385+209−137%

26Musselshell County, MTMT5,582+192−51%

27Custer County, MTMT12,034+168−16900%

28Fallon County, MTMT2,959+159−160%

29Sheridan County, MTMT3,436+155−125%

30Teton County, MTMT6,496+153−12%

31Beaverhead County, MTMT10,043+125−84%

32Deer Lodge County, MTMT9,709+123−114%

33Chouteau County, MTMT5,865+82−84%

34Treasure County, MTMT728+44−438%

35Meagher County, MTMT2,137+36−68%

36Sweet Grass County, MTMT3,762+27−94%

37Petroleum County, MTMT548+2−108%

38McCone County, MTMT1,720-5−98%

39Lincoln County, MTMT22,328-10−101%

40Dawson County, MTMT8,692-26−94%

41Garfield County, MTMT1,148-33−89%

42Phillips County, MTMT4,203-36−94%

43Powder River County, MTMT1,781-49−79%

44Judith Basin County, MTMT2,162-49−204%

45Golden Valley County, MTMT844-61−147%

46Wibaux County, MTMT885-80−35%

47Powell County, MTMT7,157-81−114%

48Daniels County, MTMT1,612-90−64%

49Prairie County, MTMT1,112-91−51%

50Wheatland County, MTMT2,100-99−862%

51Fergus County, MTMT11,825-140−26%

52Stillwater County, MTMT9,445-154−109%

53Pondera County, MTMT6,072-255+2733%

54Toole County, MTMT5,211-353−260%

55Liberty County, MTMT1,957-380+177%

56Rosebud County, MTMT8,253-904−19%

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UPDATED 2026-07-15 · DATA: US CENSUS BUREAU DECENNIAL CENSUS