Montana Counties by Population (2026)
by Kristen Carney
Updated: February 9, 2026
The most populous counties in Montana are Yellowstone County with 168,957, Gallatin County at 124,074, Missoula County with 120,672, Flathead County at 110,695, and Cascade County with 84,606. You can get the most current Census population data for all 56 Montana counties, sorted from the most populous counties in Montana to the least, according to the 2024 American Community Survey.
Sure, you can copy this list right into your favorite spreadsheet tool. Or save yourself formatting headaches and grab the latest Montana counties population data as a ready-to-use Excel™ file below. It's time to stop searching and start digging into data!
| Rank | County | Population |
|---|---|---|
| 1 | Yellowstone County | 168,957 |
| 2 | Gallatin County | 124,074 |
| 3 | Missoula County | 120,672 |
| 4 | Flathead County | 110,695 |
| 5 | Cascade County | 84,606 |
| 6 | Lewis and Clark County | 73,464 |
| 7 | Ravalli County | 46,727 |
| 8 | Silver Bow County | 35,785 |
| 9 | Lake County | 32,561 |
| 10 | Lincoln County | 21,175 |
| 11 | Park County | 17,710 |
| 12 | Hill County | 16,155 |
| 13 | Glacier County | 13,637 |
| 14 | Sanders County | 13,285 |
| 15 | Big Horn County | 12,891 |
| 16 | Jefferson County | 12,774 |
| 17 | Custer County | 11,961 |
| 18 | Fergus County | 11,687 |
| 19 | Richland County | 11,235 |
| 20 | Carbon County | 11,116 |
| 21 | Roosevelt County | 10,526 |
| 22 | Beaverhead County | 9,713 |
| 23 | Deer Lodge County | 9,597 |
| 24 | Madison County | 9,223 |
| 25 | Stillwater County | 9,182 |
| 26 | Dawson County | 8,827 |
| 27 | Rosebud County | 8,165 |
| 28 | Broadwater County | 7,668 |
| 29 | Valley County | 7,519 |
| 30 | Powell County | 7,053 |
| 31 | Blaine County | 6,949 |
| 32 | Teton County | 6,353 |
| 33 | Pondera County | 6,035 |
| 34 | Chouteau County | 5,906 |
| 35 | Musselshell County | 5,152 |
| 36 | Toole County | 5,061 |
| 37 | Mineral County | 4,959 |
| 38 | Phillips County | 4,221 |
| 39 | Sweet Grass County | 3,720 |
| 40 | Sheridan County | 3,669 |
| 41 | Granite County | 3,462 |
| 42 | Fallon County | 2,760 |
| 43 | Judith Basin County | 2,071 |
| 44 | Wheatland County | 2,056 |
| 45 | Meagher County | 2,007 |
| 46 | Liberty County | 1,952 |
| 47 | Powder River County | 1,815 |
| 48 | McCone County | 1,670 |
| 49 | Daniels County | 1,494 |
| 50 | Carter County | 1,308 |
| 51 | Prairie County | 1,250 |
| 52 | Wibaux County | 1,193 |
| 53 | Garfield County | 1,094 |
| 54 | Golden Valley County | 899 |
| 55 | Treasure County | 732 |
| 56 | Petroleum County | 447 |
|
United States Census Bureau. B01001 SEX BY AGE, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. January 29, 2026. http://www.census.gov/. |
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