# Counties in California by population aged 18 to 64, 2025

All 58 values come from U.S. Census Bureau for 2025, so the places are comparable.

- Indicator id: `population_18_64_share`
- Unit: %
- Definition: Residents aged 18 to 64 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 18 to 64 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 18 to 64 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-18-64/california-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | San Francisco County | 68.1 |
| 2 | Yolo County | 65.8 |
| 3 | Santa Clara County | 65 |
| 4 | Alameda County | 63.9 |
| 5 | Los Angeles County | 63.7 |
| 6 | San Diego County | 62.6 |
| 7 | Kings County | 62.2 |
| 8 | San Mateo County | 62.1 |
| 9 | Orange County | 62 |
| 10 | Lassen County | 61.8 |
| 11 | San Bernardino County | 61.4 |
| 12 | Mono County | 61.3 |
| 13 | Sacramento County | 60.9 |
| 14 | Santa Cruz County | 60.8 |
| 15 | San Benito County | 60.6 |
| 16 | San Joaquin County | 60.2 |
| 17 | Merced County | 60.1 |
| 18 | Solano County | 59.9 |
| 19 | Riverside County | 59.9 |
| 20 | Contra Costa County | 59.9 |
| 21 | Monterey County | 59.8 |
| 22 | Humboldt County | 59.8 |
| 23 | Ventura County | 59.5 |
| 24 | Kern County | 59.5 |
| 25 | Santa Barbara County | 59.4 |
| 26 | Yuba County | 59.4 |
| 27 | Stanislaus County | 59.2 |
| 28 | Fresno County | 59.2 |
| 29 | Butte County | 59 |
| 30 | Imperial County | 58.5 |
| 31 | Tulare County | 58.4 |
| 32 | Sutter County | 58.4 |
| 33 | Madera County | 58.4 |
| 34 | Napa County | 58.1 |
| 35 | San Luis Obispo County | 58.1 |
| 36 | Del Norte County | 57.8 |
| 37 | Sonoma County | 57.7 |
| 38 | Colusa County | 57.1 |
| 39 | Alpine County | 56.6 |
| 40 | Glenn County | 56.6 |
| 41 | Placer County | 56.5 |
| 42 | Marin County | 56 |
| 43 | Shasta County | 55 |
| 44 | El Dorado County | 54.9 |
| 45 | Trinity County | 54.8 |
| 46 | Inyo County | 54.7 |
| 47 | Tehama County | 54.3 |
| 48 | Mendocino County | 54.1 |
| 49 | Lake County | 54 |
| 50 | Amador County | 53.7 |
| 51 | Nevada County | 52.8 |
| 52 | Tuolumne County | 52.6 |
| 53 | Calaveras County | 51.6 |
| 54 | Siskiyou County | 51 |
| 55 | Mariposa County | 51 |
| 56 | Modoc County | 50.4 |
| 57 | Sierra County | 50.1 |
| 58 | Plumas County | 49.9 |