# Counties in Montana by population under 18, 2025

All 56 values come from U.S. Census Bureau for 2025, so the places are comparable.

- Indicator id: `population_0_17_share`
- Unit: %
- Definition: Residents aged 0 to 17 as a percentage of total population on 1 July. United States: Census Bureau county population estimates by age; states and the nation are sums of their counties.
- Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties (https://www.census.gov/programs-surveys/popest/data/data-sets.html)
- Retrieved: 2026-10-12
- Citation: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/population-under-18/montana-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Roosevelt County | 31.3 |
| 2 | Big Horn County | 30.2 |
| 3 | Glacier County | 28.2 |
| 4 | Rosebud County | 27.5 |
| 5 | Hill County | 27 |
| 6 | Blaine County | 26.6 |
| 7 | Fallon County | 24.7 |
| 8 | Garfield County | 24.1 |
| 9 | Liberty County | 24 |
| 10 | Richland County | 23.9 |
| 11 | Teton County | 23.8 |
| 12 | Phillips County | 22.7 |
| 13 | Pondera County | 22.7 |
| 14 | Treasure County | 22.4 |
| 15 | Wibaux County | 22 |
| 16 | Yellowstone County | 21.8 |
| 17 | Valley County | 21.5 |
| 18 | Chouteau County | 21.4 |
| 19 | Cascade County | 21.3 |
| 20 | Carter County | 21.3 |
| 21 | Dawson County | 21.2 |
| 22 | Broadwater County | 21.2 |
| 23 | Fergus County | 21.2 |
| 24 | Flathead County | 21.2 |
| 25 | Wheatland County | 21 |
| 26 | Custer County | 21 |
| 27 | Musselshell County | 20.9 |
| 28 | Toole County | 20.8 |
| 29 | Daniels County | 20.7 |
| 30 | Stillwater County | 20.7 |
| 31 | Lake County | 20.7 |
| 32 | Lewis and Clark County | 20.2 |
| 33 | McCone County | 20.1 |
| 34 | Prairie County | 20.1 |
| 35 | Jefferson County | 19.9 |
| 36 | Golden Valley County | 19.7 |
| 37 | Sheridan County | 19.4 |
| 38 | Powder River County | 19.3 |
| 39 | Silver Bow County | 18.9 |
| 40 | Judith Basin County | 18.5 |
| 41 | Ravalli County | 18.4 |
| 42 | Lincoln County | 18.1 |
| 43 | Gallatin County | 17.7 |
| 44 | Missoula County | 17.6 |
| 45 | Carbon County | 17.5 |
| 46 | Sweet Grass County | 17.1 |
| 47 | Mineral County | 17 |
| 48 | Meagher County | 16.8 |
| 49 | Beaverhead County | 16.7 |
| 50 | Sanders County | 16.4 |
| 51 | Petroleum County | 16.4 |
| 52 | Park County | 16.4 |
| 53 | Madison County | 15.8 |
| 54 | Granite County | 15.4 |
| 55 | Powell County | 15.2 |
| 56 | Deer Lodge County | 14.6 |