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Population Review

Census ACS · 56 counties

Largest Counties in Montana

Montana has 56 counties with Census data available. The largest is Yellowstone County with a population of 167,340. County-level data is important because counties are the primary unit of local government in most states, responsible for courts, elections, public health, and infrastructure. Population distribution across counties reveals where growth is concentrated and where rural decline may be occurring.

Source: Census ACS 5-Year Estimates

#CountyPopulationMedian Income
1Yellowstone County167,340$74,400
2Wibaux County1,148$64,792
3Wheatland County2,049$47,054
4Valley County7,540$64,515
5Treasure County761$73,036
6Toole County5,028$53,693
7Teton County6,291$67,766
8Sweet Grass County3,713$69,426
9Stillwater County9,052$81,503
10Silver Bow County35,589$57,504
11Sheridan County3,677$63,654
12Sanders County12,936$54,035
13Rosebud County8,236$56,430
14Roosevelt County10,665$53,125
15Richland County11,329$69,578
16Ravalli County45,807$71,323
17Prairie County1,251$45,192
18Powell County7,029$63,432
19Powder River County1,762$68,009
20Pondera County6,012$53,500
21Phillips County4,224$58,156
22Petroleum County401$59,318
23Park County17,484$66,607
24Musselshell County5,068$59,010
25Missoula County119,639$71,246
26Mineral County4,796$61,117
27Meagher County1,979$56,215
28McCone County1,818$71,842
29Madison County8,975$67,420
30Lincoln County20,656$47,018
31Liberty County1,968$53,264
32Lewis and Clark County72,580$74,543
33Lake County32,073$61,965
34Judith Basin County2,053$55,417
35Jefferson County12,501$76,576
36Hill County16,260$55,313
37Granite County3,419$54,646
38Golden Valley County840$57,353
39Glacier County13,713$45,129
40Garfield County938$61,750
41Gallatin County122,194$87,454
42Flathead County108,445$71,327
43Fergus County11,581$59,731
44Fallon County2,817$72,284
45Deer Lodge County9,512$49,533
46Dawson County8,874$70,953
47Daniels County1,524$58,000
48Custer County11,938$63,585
49Chouteau County5,888$56,927
50Cascade County84,601$66,203
51Carter County1,361$52,171
52Carbon County10,877$71,017
53Broadwater County7,310$63,636
54Blaine County6,997$65,050
55Big Horn County12,963$56,680
56Beaverhead County9,590$58,072

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Frequently Asked Questions

Yellowstone County is the #1 ranked county in Montana by population, with a value of 167,340 according to latest Census ACS data.

Montana has 56 counties tracked in latest Census ACS data.

All data comes from the American Community Survey (ACS) 5-Year estimates by the US Census Bureau.

Sources: US Census Bureau ACS 5-Year Estimates

Data from the American Community Survey 5-Year estimates. Covers all counties in Montana.

Source: U.S. Census Bureau ACS, 2026.