RANKING · 2010 CENSUS · 56 SHOWN OF 56

Largest by population, Montana counties · 2010

The most populous Montana counties as of the 2010 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, MTMT147,972+14%

02Missoula County, MTMT109,299+14%

03Flathead County, MTMT90,928+22%

04Gallatin County, MTMT89,513+32%

05Cascade County, MTMT81,327+1%

06Lewis and Clark County, MTMT63,395+14%

07Ravalli County, MTMT40,212+11%

08Silver Bow County, MTMT34,200−1%

09Lake County, MTMT28,746+8%

10Lincoln County, MTMT19,687+5%

11Hill County, MTMT16,096−3%

12Park County, MTMT15,636−0%

13Glacier County, MTMT13,399+1%

14Big Horn County, MTMT12,865+2%

15Custer County, MTMT11,699+0%

16Fergus County, MTMT11,586−3%

17Sanders County, MTMT11,413+12%

18Jefferson County, MTMT11,406+14%

19Roosevelt County, MTMT10,425−2%

20Carbon County, MTMT10,078+6%

21Richland County, MTMT9,746+1%

22Deer Lodge County, MTMT9,298−1%

23Beaverhead County, MTMT9,246+0%

24Rosebud County, MTMT9,233−2%

25Stillwater County, MTMT9,117+11%

26Dawson County, MTMT8,966−1%

27Madison County, MTMT7,691+12%

28Valley County, MTMT7,369−4%

29Powell County, MTMT7,027−2%

30Blaine County, MTMT6,491−7%

31Pondera County, MTMT6,153−4%

32Teton County, MTMT6,073−6%

33Chouteau County, MTMT5,813−3%

34Broadwater County, MTMT5,612+28%

35Toole County, MTMT5,324+1%

36Musselshell County, MTMT4,538+1%

37Phillips County, MTMT4,253−8%

38Mineral County, MTMT4,223+9%

39Sweet Grass County, MTMT3,651+1%

40Sheridan County, MTMT3,384−18%

41Granite County, MTMT3,079+9%

42Fallon County, MTMT2,890+2%

43Liberty County, MTMT2,339+8%

44Wheatland County, MTMT2,168−4%

45Judith Basin County, MTMT2,072−11%

46Meagher County, MTMT1,891−2%

47Daniels County, MTMT1,751−13%

48Powder River County, MTMT1,743−6%

49McCone County, MTMT1,734−12%

50Garfield County, MTMT1,206−6%

51Prairie County, MTMT1,179−2%

52Carter County, MTMT1,160−15%

53Wibaux County, MTMT1,017−5%

54Golden Valley County, MTMT884−15%

55Treasure County, MTMT718−17%

56Petroleum County, MTMT494+0%

SHOWING 1–56 OF 56

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