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

All 58 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/california-counties

| Rank | Place | years |
|---:|---|---:|
| 1 | Sierra County | 55.2 |
| 2 | Plumas County | 52.6 |
| 3 | Alpine County | 51.4 |
| 4 | Amador County | 50.2 |
| 4 | Calaveras County | 50.2 |
| 6 | Trinity County | 49.8 |
| 7 | Nevada County | 49.3 |
| 8 | Mariposa County | 49.2 |
| 9 | Modoc County | 48.6 |
| 10 | Tuolumne County | 48.1 |
| 11 | Marin County | 48 |
| 11 | Siskiyou County | 48 |
| 13 | El Dorado County | 46.8 |
| 14 | Mendocino County | 45 |
| 15 | Inyo County | 44.9 |
| 16 | Napa County | 44.4 |
| 17 | Lake County | 44.1 |
| 17 | Sonoma County | 44.1 |
| 19 | Placer County | 42.7 |
| 20 | Shasta County | 42.4 |
| 21 | San Luis Obispo County | 41.7 |
| 22 | Santa Cruz County | 41.5 |
| 23 | Contra Costa County | 41.4 |
| 23 | Del Norte County | 41.4 |
| 23 | Mono County | 41.4 |
| 26 | San Mateo County | 41.3 |
| 27 | Humboldt County | 41 |
| 28 | Ventura County | 40.9 |
| 29 | Orange County | 40.4 |
| 29 | Tehama County | 40.4 |
| 31 | Solano County | 40.1 |
| 32 | San Francisco County | 40 |
| 33 | Alameda County | 39.6 |
| 34 | Los Angeles County | 39.1 |
| 35 | Lassen County | 38.7 |
| 36 | Santa Clara County | 38.4 |
| 37 | Glenn County | 38 |
| 37 | Sacramento County | 38 |
| 37 | San Diego County | 38 |
| 40 | Butte County | 37.9 |
| 41 | Riverside County | 37.8 |
| 42 | San Benito County | 37.6 |
| 43 | Sutter County | 37.4 |
| 44 | Monterey County | 36.5 |
| 45 | Colusa County | 36.3 |
| 45 | San Joaquin County | 36.3 |
| 47 | Stanislaus County | 36 |
| 48 | San Bernardino County | 35.9 |
| 48 | Santa Barbara County | 35.9 |
| 50 | Yuba County | 35.2 |
| 51 | Madera County | 35 |
| 52 | Imperial County | 34.8 |
| 53 | Fresno County | 34.3 |
| 54 | Kern County | 33.7 |
| 54 | Kings County | 33.7 |
| 56 | Tulare County | 33.2 |
| 57 | Merced County | 32.9 |
| 58 | Yolo County | 32.2 |