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. The median across all 56 is 8,253.

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SAME RANKING BYCities States Metros ZIP codes

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%

13▲2Sanders County, MTMT14,062+37%

14▼1Glacier County, MTMT13,463+2%

15▲1Jefferson County, MTMT13,329+33%

16▼2Big Horn County, MTMT12,752+1%

17Custer County, MTMT12,034+3%

18▲1Fergus County, MTMT11,825−1%

19▲2Carbon County, MTMT11,466+20%

20▼2Richland County, MTMT11,377+18%

21▼1Roosevelt County, MTMT10,242−4%

22▲1Beaverhead County, MTMT10,043+9%

23▲3Madison County, MTMT10,026+46%

24▼2Deer Lodge County, MTMT9,709+3%

25▼1Stillwater County, MTMT9,445+15%

26▼1Dawson County, MTMT8,692−4%

27▲4Broadwater County, MTMT8,493+94%

28▼1Rosebud County, MTMT8,253−12%

29▼1Valley County, MTMT7,385−4%

30Powell County, MTMT7,1570%

31▼2Blaine County, MTMT6,860−2%

32Teton County, MTMT6,496+1%

33Pondera County, MTMT6,072−5%

34Chouteau County, MTMT5,865−2%

35▲1Musselshell County, MTMT5,582+24%

36▼1Toole County, MTMT5,211−1%

37Mineral County, MTMT5,185+33%

38Phillips County, MTMT4,203−9%

39Sweet Grass County, MTMT3,762+4%

40▲1Granite County, MTMT3,658+29%

41▼1Sheridan County, MTMT3,436−16%

42Fallon County, MTMT2,959+4%

43▲1Judith Basin County, MTMT2,162−7%

44▲2Meagher County, MTMT2,137+11%

45▼2Wheatland County, MTMT2,100−7%

46▼1Liberty County, MTMT1,957−9%

47▲1Powder River County, MTMT1,781−4%

48▼1McCone 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 2026-09-11 · DATA: US CENSUS BUREAU POPULATION ESTIMATES