RANKING · 2025 ESTIMATES · 56 SHOWN OF 56

Largest by population, Montana counties

The most populous Montana counties as of the 2025 population estimates. This list covers the 56 counties in Montana that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDFastest growing Fastest shrinking Most population gained Most population lost Most densely populated Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATETOTAL POPULATIONVS 2000

01Yellowstone County, MTMT172,692+34%

02Gallatin County, MTMT128,740+90%

03Missoula County, MTMT123,513+29%

04Flathead County, MTMT115,429+55%

05Cascade County, MTMT85,029+6%

06Lewis and Clark County, MTMT75,331+35%

07Ravalli County, MTMT48,582+35%

08Silver Bow County, MTMT36,118+4%

09Lake County, MTMT33,392+26%

10Lincoln County, MTMT22,328+19%

11Park County, MTMT18,214+16%

12Hill County, MTMT16,167−3%

13Sanders County, MTMT14,062+37%

14Glacier County, MTMT13,463+2%

15Jefferson County, MTMT13,329+33%

16Big Horn County, MTMT12,752+1%

17Custer County, MTMT12,034+3%

18Fergus County, MTMT11,825−1%

19Carbon County, MTMT11,466+20%

20Richland County, MTMT11,377+18%

21Roosevelt County, MTMT10,242−4%

22Beaverhead County, MTMT10,043+9%

23Madison County, MTMT10,026+46%

24Deer Lodge County, MTMT9,709+3%

25Stillwater County, MTMT9,445+15%

26Dawson County, MTMT8,692−4%

27Broadwater County, MTMT8,493+94%

28Rosebud County, MTMT8,253−12%

29Valley County, MTMT7,385−4%

30Powell County, MTMT7,157−0%

31Blaine County, MTMT6,860−2%

32Teton County, MTMT6,496+1%

33Pondera County, MTMT6,072−5%

34Chouteau County, MTMT5,865−2%

35Musselshell County, MTMT5,582+24%

36Toole County, MTMT5,211−1%

37Mineral County, MTMT5,185+33%

38Phillips County, MTMT4,203−9%

39Sweet Grass County, MTMT3,762+4%

40Granite County, MTMT3,658+29%

41Sheridan County, MTMT3,436−16%

42Fallon County, MTMT2,959+4%

43Judith Basin County, MTMT2,162−7%

44Meagher County, MTMT2,137+11%

45Wheatland County, MTMT2,100−7%

46Liberty County, MTMT1,957−9%

47Powder River County, MTMT1,781−4%

48McCone County, MTMT1,720−13%

49Daniels County, MTMT1,612−20%

50Carter County, MTMT1,383+2%

51Garfield County, MTMT1,148−10%

52Prairie County, MTMT1,112−7%

53Wibaux County, MTMT885−17%

54Golden Valley County, MTMT844−19%

55Treasure County, MTMT728−15%

56Petroleum County, MTMT548+11%

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