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

All 39 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/washington-counties

| Rank | Place | years |
|---:|---|---:|
| 1 | Jefferson County | 61.7 |
| 2 | San Juan County | 57 |
| 3 | Pacific County | 54.4 |
| 4 | Wahkiakum County | 54.1 |
| 5 | Clallam County | 53.6 |
| 6 | Columbia County | 50.6 |
| 7 | Pend Oreille County | 50 |
| 8 | Ferry County | 49.7 |
| 9 | Skamania County | 48 |
| 10 | Island County | 47.5 |
| 11 | Stevens County | 47.4 |
| 12 | Lincoln County | 46.8 |
| 13 | Garfield County | 46.5 |
| 14 | Klickitat County | 46.3 |
| 15 | Asotin County | 45.9 |
| 16 | Grays Harbor County | 45.2 |
| 17 | Mason County | 45.1 |
| 18 | Okanogan County | 43.4 |
| 19 | Skagit County | 43.3 |
| 20 | Lewis County | 42.2 |
| 21 | Chelan County | 41.4 |
| 22 | Cowlitz County | 41.2 |
| 23 | Kitsap County | 41.1 |
| 24 | Thurston County | 40.7 |
| 25 | Walla Walla County | 40.1 |
| 26 | Clark County | 39.8 |
| 27 | Spokane County | 39.1 |
| 27 | Whatcom County | 39.1 |
| 29 | Douglas County | 39 |
| 30 | Snohomish County | 38.8 |
| 31 | Pierce County | 37.9 |
| 32 | King County | 37.5 |
| 33 | Benton County | 36.9 |
| 34 | Kittitas County | 36.5 |
| 35 | Grant County | 34.6 |
| 35 | Yakima County | 34.6 |
| 37 | Franklin County | 31.7 |
| 38 | Adams County | 30 |
| 39 | Whitman County | 25.9 |