RANKING · 2020 CENSUS · 56 SHOWN OF 56

Most population lost, Montana counties · 2020

Montana counties that lost 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. The median across all 56 is +159.

Flip the list · Most population gained, US counties →

MontanaAll states All rankings

SAME RANKING BYCities States Metros

RELATEDLargest by population Fastest growing Fastest shrinking Most population gained Most densely populated Most sparsely populated

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01Rosebud County, MTMT8,253-904−19%

02Liberty County, MTMT1,957-380+177%

03Toole County, MTMT5,211-353−260%

04Pondera County, MTMT6,072-255+2733%

05Stillwater County, MTMT9,445-154−109%

06Fergus County, MTMT11,825-140−26%

07Wheatland County, MTMT2,100-99−862%

08Prairie County, MTMT1,112-91−51%

09Daniels County, MTMT1,612-90−64%

10Powell County, MTMT7,157-81−114%

11Wibaux County, MTMT885-80−35%

12Golden Valley County, MTMT844-61−147%

13Powder River County, MTMT1,781-49−79%

14Judith Basin County, MTMT2,162-49−204%

15Phillips County, MTMT4,203-36−94%

16Garfield County, MTMT1,148-33−89%

17Dawson County, MTMT8,692-26−94%

18Lincoln County, MTMT22,328-10−101%

19McCone County, MTMT1,720-5−98%

20Petroleum County, MTMT548+2−108%

21Sweet Grass County, MTMT3,762+27−94%

22Meagher County, MTMT2,137+36−68%

23Treasure County, MTMT728+44−438%

24Chouteau County, MTMT5,865+82−84%

25Deer Lodge County, MTMT9,709+123−114%

26Beaverhead County, MTMT10,043+125−84%

27Teton County, MTMT6,496+153−12%

28Sheridan County, MTMT3,436+155−125%

29Fallon County, MTMT2,959+159−160%

30Custer County, MTMT12,034+168−16900%

31Musselshell County, MTMT5,582+192−51%

32Valley County, MTMT7,385+209−137%

33Hill County, MTMT16,167+213−122%

34Granite County, MTMT3,658+230−18%

35Carter County, MTMT1,383+255−278%

36Big Horn County, MTMT12,752+259−81%

37Mineral County, MTMT5,185+312−45%

38Roosevelt County, MTMT10,242+369−197%

39Glacier County, MTMT13,463+379−66%

40Carbon County, MTMT11,466+395−73%

41Blaine County, MTMT6,860+553+97%

42Jefferson County, MTMT13,329+679−68%

43Madison County, MTMT10,026+932+8%

44Silver Bow County, MTMT36,118+933+40%

45Sanders County, MTMT14,062+987−37%

46Broadwater County, MTMT8,493+1,162+9%

47Park County, MTMT18,214+1,555+37%

48Richland County, MTMT11,377+1,745−266%

49Lake County, MTMT33,392+2,388−56%

50Cascade County, MTMT85,029+3,087+16%

51Ravalli County, MTMT48,582+3,962−64%

52Lewis and Clark County, MTMT75,331+7,578−8%

53Missoula County, MTMT123,513+8,623−50%

54Flathead County, MTMT115,429+13,429−12%

55Yellowstone County, MTMT172,692+16,759+5%

56Gallatin County, MTMT128,740+29,447+70%

SHOWING 1–56 OF 56

Download CSV (full list, 56 rows)

UPDATED 2026-09-11 · DATA: US CENSUS BUREAU DECENNIAL CENSUS