# Counties in Idaho by median age on 1 July (US county estimates), 2025

All 44 values come from U.S. Census Bureau for 2025, so the places are comparable.

- Indicator id: `median_age_pep`
- Unit: years
- Definition: Age that divides the resident population of a US county into two halves of equal size on 1 July, from Census Bureau population estimates calculated by single year of age.
- Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage (https://www.census.gov/programs-surveys/popest/data/data-sets.html)
- Publisher page: https://invokely.ai/en/publishers/us-census-bureau
- Retrieved: 2026-10-12
- Citation: U.S. Census Bureau. Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/median-age-july-1-us-counties/idaho-counties

| Rank | Place | years |
|---:|---|---:|
| 1 | Boise County | 54.3 |
| 2 | Adams County | 53.4 |
| 3 | Custer County | 52.1 |
| 4 | Lemhi County | 51.8 |
| 5 | Clearwater County | 51.6 |
| 6 | Idaho County | 50.5 |
| 7 | Valley County | 50.2 |
| 8 | Camas County | 50.1 |
| 9 | Bonner County | 48.1 |
| 10 | Lewis County | 47.4 |
| 11 | Blaine County | 46.5 |
| 12 | Washington County | 46.1 |
| 13 | Benewah County | 45.8 |
| 14 | Shoshone County | 45.6 |
| 15 | Butte County | 45 |
| 15 | Gem County | 45 |
| 17 | Boundary County | 44.9 |
| 18 | Nez Perce County | 42.1 |
| 19 | Kootenai County | 41.9 |
| 20 | Bear Lake County | 41.6 |
| 21 | Teton County | 40.9 |
| 22 | Payette County | 40.2 |
| 23 | Owyhee County | 39.7 |
| 24 | Clark County | 39.3 |
| 25 | Ada County | 39.1 |
| 25 | Oneida County | 39.1 |
| 27 | Fremont County | 38.5 |
| 28 | Gooding County | 38 |
| 29 | Caribou County | 37.8 |
| 30 | Twin Falls County | 36.9 |
| 31 | Bingham County | 35.8 |
| 31 | Lincoln County | 35.8 |
| 33 | Bannock County | 35.6 |
| 33 | Power County | 35.6 |
| 35 | Minidoka County | 35.5 |
| 36 | Canyon County | 35.2 |
| 37 | Franklin County | 34.6 |
| 38 | Elmore County | 34.5 |
| 39 | Bonneville County | 34.2 |
| 39 | Jerome County | 34.2 |
| 41 | Jefferson County | 34.1 |
| 42 | Cassia County | 33.1 |
| 43 | Latah County | 31.6 |
| 44 | Madison County | 22.5 |