# Counties in Idaho by population under 18, 2025

All 44 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/idaho-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Jefferson County | 30.3 |
| 2 | Cassia County | 29.5 |
| 3 | Franklin County | 29.4 |
| 4 | Jerome County | 29.1 |
| 5 | Bonneville County | 28 |
| 6 | Oneida County | 28 |
| 7 | Caribou County | 27.9 |
| 8 | Bingham County | 27.6 |
| 9 | Power County | 27.2 |
| 10 | Minidoka County | 27.1 |
| 11 | Clark County | 26.3 |
| 12 | Lincoln County | 26.2 |
| 13 | Canyon County | 25.8 |
| 14 | Twin Falls County | 25.2 |
| 15 | Bear Lake County | 25.1 |
| 16 | Gooding County | 24.6 |
| 17 | Bannock County | 24.4 |
| 18 | Payette County | 24.3 |
| 19 | Fremont County | 24.3 |
| 20 | Elmore County | 23.4 |
| 21 | Boundary County | 23.4 |
| 22 | Owyhee County | 23.3 |
| 23 | Butte County | 23.2 |
| 24 | Gem County | 21.9 |
| 25 | Kootenai County | 21.8 |
| 26 | Benewah County | 21.6 |
| 26 | Madison County | 21.6 |
| 28 | Ada County | 21 |
| 29 | Washington County | 20.9 |
| 30 | Teton County | 20.8 |
| 31 | Nez Perce County | 20.4 |
| 32 | Lewis County | 20.4 |
| 33 | Shoshone County | 20.4 |
| 34 | Latah County | 19.9 |
| 35 | Idaho County | 19.4 |
| 36 | Bonner County | 19.3 |
| 37 | Camas County | 19.3 |
| 38 | Lemhi County | 17.7 |
| 39 | Valley County | 17.5 |
| 40 | Blaine County | 17.5 |
| 41 | Custer County | 17 |
| 42 | Adams County | 16.1 |
| 43 | Clearwater County | 15.7 |
| 44 | Boise County | 15.4 |