Counties in California by population aged 18 to 64
San Francisco County had the highest population aged 18 to 64 of 58 counties in 2021, at 68.6%. Modoc County had the lowest, at 52.2%. The median was 59.4% and the figure for California was 62.2%. Source: the U.S. Census Bureau.
All counties, 2021
Full ranking
Other periods
About this ranking
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.
Not comparable with working-age shares for ages 15 to 64 used in EU and World Bank statistics.
Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.
How to cite
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 styles
APA 7
U.S. Census Bureau. (2026). 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 (Counties in California by population aged 18 to 64, 2021) [Data set]. Retrieved October 12, 2026, from https://www.census.gov/programs-surveys/popest/data/data-sets.html
MLA 9
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, Counties in California by population aged 18 to 64, 2021. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-18-64/california-counties?period=2021. Accessed 12 Oct. 2026.
Chicago (author-date)
U.S. Census Bureau. 2026. 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. Counties in California by population aged 18 to 64, 2021. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/population-18-64/california-counties?period=2021.
Harvard
U.S. Census Bureau (2026) 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, Counties in California by population aged 18 to 64, 2021 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-18-64/california-counties?period=2021 (Accessed: 12 October 2026).
BibTeX
@misc{census_counties_in_california_by_2021,
author = {{U.S. Census Bureau}},
title = {{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: Counties in California by population aged 18 to 64, 2021}},
year = {2026},
howpublished = {Data set},
url = {https://www.census.gov/programs-surveys/popest/data/data-sets.html},
urldate = {2026-10-12},
note = {Accessed via Invokely, https://invokely.ai/rankings/population-18-64/california-counties?period=2021. Publisher attribution: 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.},
}
RIS
TY - DATA
AU - U.S. Census Bureau
TI - 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: Counties in California by population aged 18 to 64, 2021
PY - 2026
DA - 2026/06/25
PB - U.S. Census Bureau
DB - Invokely
UR - https://www.census.gov/programs-surveys/popest/data/data-sets.html
L2 - https://invokely.ai/rankings/population-18-64/california-counties?period=2021
Y2 - 2026/10/12
N1 - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/california-counties?period=2021.
N1 - Publisher attribution: 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.
ER -
Use this data in your AI agent
Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:
Rank Counties in California by population aged 18 to 64 using official data, and cite the source.
rank_places {"indicator":"population_18_64_share","level":"province","within":"California","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=population_18_64_share&level=province&within=California&limit=10Questions
Which county has the highest population aged 18 to 64?
San Francisco County, with 68.6% in 2021, according to the U.S. Census Bureau.
Which county has the lowest population aged 18 to 64?
Modoc County, with 52.2% in 2021.
Where does this ranking come from?
Every value comes from one source and one period, so the places are comparable: 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. Retrieved 2026-10-12.
Population aged 18 to 64: other rankings
Counties in California: more rankings
- Net domestic migration, July to June
- High school graduate or higher, population 25 and over
- Crude birth rate, July to June
- Net domestic migration rate, July to June
- Current asthma in adults, local model estimate
- Uninsured rate, ages 18 to 64 (US model-based estimate)
- Traffic fatality rate
- Fair Market Rent, efficiency (HUD, monthly)