Montana Population By County in 2021 (ACS-5Yrs)
Updated on February 28, 2025.
Based on the US Census ACS-5Yrs estimates, in 2021, the total population of Montana was 1.08M. Among all Montana counties, Yellowstone was the most populated county (163.59K), followed by Missoula (117.38K), and then Gallatin (116.73K).
On the other hand, the least populated counties were: Petroleum (434), Treasure (693), and Golden Valley (820).
The chart and table below shows the population of each county and the percentage of Montana population in each county.
You can see similar information for other states and by state for the United States.
Related Topics: Montana ACS-5Yrs Estimates, 2021 Topic List.
Data Source: US Census - ACS 5-Year Estimates, 2021 Census.
Montana Population By County in 2021
Montana Population By County in 2021
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| County | Population | % of State Population |
|---|---|---|
| Beaverhead | 9391 | 0.87 |
| Big Horn | 13198 | 1.22 |
| Blaine | 7051 | 0.65 |
| Broadwater | 6641 | 0.62 |
| Carbon | 10488 | 0.97 |
| Carter | 1349 | 0.13 |
| Cascade | 84178 | 7.81 |
| Chouteau | 5896 | 0.55 |
| Custer | 11968 | 1.11 |
| Daniels | 1739 | 0.16 |
| Dawson | 9003 | 0.84 |
| Deer Lodge | 9380 | 0.87 |
| Fallon | 3074 | 0.28 |
| Fergus | 11464 | 1.06 |
| Flathead | 103400 | 9.59 |
| Gallatin | 116725 | 10.83 |
| Garfield | 972 | 0.09 |
| Glacier | 13827 | 1.28 |
| Golden Valley | 820 | 0.08 |
| Granite | 3333 | 0.31 |
| Hill | 16297 | 1.51 |
| Jefferson | 12057 | 1.12 |
| Judith Basin | 2004 | 0.19 |
| Lake | 31030 | 2.88 |
| Lewis and Clark | 70340 | 6.53 |
| Liberty | 2026 | 0.19 |
| Lincoln | 19674 | 1.83 |
| McCone | 1805 | 0.17 |
| Madison | 8499 | 0.79 |
| Meagher | 1932 | 0.18 |
| Mineral | 4490 | 0.42 |
| Missoula | 117379 | 10.89 |
| Musselshell | 4813 | 0.45 |
| Park | 17072 | 1.58 |
| Petroleum | 434 | 0.04 |
| Phillips | 4233 | 0.39 |
| Pondera | 5974 | 0.55 |
| Powder River | 1759 | 0.16 |
| Powell | 6955 | 0.65 |
| Prairie | 1227 | 0.11 |
| Ravalli | 43790 | 4.06 |
| Richland | 11375 | 1.06 |
| Roosevelt | 10884 | 1.01 |
| Rosebud | 8464 | 0.79 |
| Sanders | 12298 | 1.14 |
| Sheridan | 3522 | 0.33 |
| Silver Bow | 35017 | 3.25 |
| Stillwater | 8916 | 0.83 |
| Sweet Grass | 3690 | 0.34 |
| Teton | 6173 | 0.57 |
| Toole | 5013 | 0.47 |
| Treasure | 693 | 0.06 |
| Valley | 7553 | 0.70 |
| Wheatland | 2082 | 0.19 |
| Wibaux | 1018 | 0.09 |
| Yellowstone | 163593 | 15.18 |