Ranking of Montana Counties By Population in 2020
Updated on June 18, 2025.
Based on the US Census Vintage data estimates, in 2020, the Population for Montana was 1.09M. Among all Montana counties, Yellowstone County had the highest population (165.21K), followed by Gallatin County (119.61K), and Missoula County (118.35K).
The chart below shows the top 10 counties, and the table below shows the ranking of all Montana counties.
You can see similar ranking information for related topics, and for other states. You can also see the ranking of all counties in the United States.
Related Topics: Montana Census Vintage Data Topic List.
Data Source: US Census Bureau (Vintage), 2020 Census.
See this for other years:
Ranking of Montana Counties By Population in 2020
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| Rank | County | Population |
|---|---|---|
| 1 | Yellowstone County | 165210 |
| 2 | Gallatin County | 119607 |
| 3 | Missoula County | 118353 |
| 4 | Flathead County | 104881 |
| 5 | Cascade County | 84411 |
| 6 | Lewis and Clark County | 71179 |
| 7 | Ravalli County | 44417 |
| 8 | Silver Bow County | 35210 |
| 9 | Lake County | 31247 |
| 10 | Lincoln County | 19744 |
| 11 | Park County | 17229 |
| 12 | Hill County | 16253 |
| 13 | Glacier County | 13744 |
| 14 | Big Horn County | 13083 |
| 15 | Sanders County | 12461 |
| 16 | Jefferson County | 12142 |
| 17 | Custer County | 11863 |
| 18 | Richland County | 11534 |
| 19 | Fergus County | 11470 |
| 20 | Roosevelt County | 10802 |
| 21 | Carbon County | 10514 |
| 22 | Deer Lodge County | 9423 |
| 23 | Beaverhead County | 9377 |
| 24 | Stillwater County | 9002 |
| 25 | Dawson County | 8922 |
| 26 | Madison County | 8661 |
| 27 | Rosebud County | 8306 |
| 28 | Valley County | 7561 |
| 29 | Blaine County | 7003 |
| 30 | Powell County | 6938 |
| 31 | Broadwater County | 6863 |
| 32 | Teton County | 6253 |
| 33 | Chouteau County | 5917 |
| 34 | Pondera County | 5877 |
| 35 | Toole County | 4967 |
| 36 | Musselshell County | 4749 |
| 37 | Mineral County | 4568 |
| 38 | Phillips County | 4211 |
| 39 | Sweet Grass County | 3670 |
| 40 | Sheridan County | 3536 |
| 41 | Granite County | 3306 |
| 42 | Fallon County | 3029 |
| 43 | Wheatland County | 2072 |
| 44 | Judith Basin County | 2023 |
| 45 | Liberty County | 1958 |
| 46 | Meagher County | 1924 |
| 47 | McCone County | 1729 |
| 48 | Powder River County | 1693 |
| 49 | Daniels County | 1653 |
| 50 | Carter County | 1407 |
| 51 | Garfield County | 1171 |
| 52 | Prairie County | 1090 |
| 53 | Wibaux County | 936 |
| 54 | Golden Valley County | 821 |
| 55 | Treasure County | 758 |
| 56 | Petroleum County | 502 |