Data / Rankings / Median age on 1 July (US county estimates) / Counties in California

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

Sierra County had the highest median age on 1 July (US county estimates) of 58 counties in 2025, at 55.2 years. Yolo County had the lowest, at 32.2 years. The median was 40.4 years. Source: the U.S. Census Bureau.

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Highest55.2Sierra County
Lowest32.2Yolo County
Median40.458 counties

Map of counties, 2025

Alameda County: 39.6 yearsAlpine County: 51.4 yearsAmador County: 50.2 yearsButte County: 37.9 yearsCalaveras County: 50.2 yearsColusa County: 36.3 yearsContra Costa County: 41.4 yearsDel Norte County: 41.4 yearsEl Dorado County: 46.8 yearsFresno County: 34.3 yearsGlenn County: 38 yearsHumboldt County: 41 yearsImperial County: 34.8 yearsInyo County: 44.9 yearsKern County: 33.7 yearsKings County: 33.7 yearsLake County: 44.1 yearsLassen County: 38.7 yearsLos Angeles County: 39.1 yearsMadera County: 35 yearsMarin County: 48 yearsMariposa County: 49.2 yearsMendocino County: 45 yearsMerced County: 32.9 yearsModoc County: 48.6 yearsMono County: 41.4 yearsMonterey County: 36.5 yearsNapa County: 44.4 yearsNevada County: 49.3 yearsOrange County: 40.4 yearsPlacer County: 42.7 yearsPlumas County: 52.6 yearsRiverside County: 37.8 yearsSacramento County: 38 yearsSan Benito County: 37.6 yearsSan Bernardino County: 35.9 yearsSan Diego County: 38 yearsSan Francisco County: 40 yearsSan Joaquin County: 36.3 yearsSan Luis Obispo County: 41.7 yearsSan Mateo County: 41.3 yearsSanta Barbara County: 35.9 yearsSanta Clara County: 38.4 yearsSanta Cruz County: 41.5 yearsShasta County: 42.4 yearsSierra County: 55.2 yearsSiskiyou County: 48 yearsSolano County: 40.1 yearsSonoma County: 44.1 yearsStanislaus County: 36 yearsSutter County: 37.4 yearsTehama County: 40.4 yearsTrinity County: 49.8 yearsTulare County: 33.2 yearsTuolumne County: 48.1 yearsVentura County: 40.9 yearsYolo County: 32.2 yearsYuba County: 35.2 years
  • Under 36
  • 36 to 38
  • 38 to 40
  • 40 to 42
  • 42 to 48
  • 48 and over
years, 2025. 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. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2025

Sierra County: 55.2 yearsSierra County55.2Plumas County: 52.6 yearsPlumas County52.6Alpine County: 51.4 yearsAlpine County51.4Amador County: 50.2 yearsAmador County50.2Calaveras County: 50.2 yearsCalaveras County50.2Trinity County: 49.8 yearsTrinity County49.8Nevada County: 49.3 yearsNevada County49.3Mariposa County: 49.2 yearsMariposa County49.2Modoc County: 48.6 yearsModoc County48.6Tuolumne County: 48.1 yearsTuolumne County48.1Marin County: 48 yearsMarin County48Siskiyou County: 48 yearsSiskiyou County48El Dorado County: 46.8 yearsEl Dorado County46.8Mendocino County: 45 yearsMendocino County45Inyo County: 44.9 yearsInyo County44.9Napa County: 44.4 yearsNapa County44.4Lake County: 44.1 yearsLake County44.1Sonoma County: 44.1 yearsSonoma County44.1Placer County: 42.7 yearsPlacer County42.7Shasta County: 42.4 yearsShasta County42.4San Luis Obispo County: 41.7 yearsSan Luis Obispo County41.7Santa Cruz County: 41.5 yearsSanta Cruz County41.5Contra Costa County: 41.4 yearsContra Costa County41.4Del Norte County: 41.4 yearsDel Norte County41.4Mono County: 41.4 yearsMono County41.4San Mateo County: 41.3 yearsSan Mateo County41.3Humboldt County: 41 yearsHumboldt County41Ventura County: 40.9 yearsVentura County40.9Orange County: 40.4 yearsOrange County40.4Tehama County: 40.4 yearsTehama County40.4Solano County: 40.1 yearsSolano County40.1San Francisco County: 40 yearsSan Francisco County40Alameda County: 39.6 yearsAlameda County39.6Los Angeles County: 39.1 yearsLos Angeles County39.1Lassen County: 38.7 yearsLassen County38.7Santa Clara County: 38.4 yearsSanta Clara County38.4Glenn County: 38 yearsGlenn County38Sacramento County: 38 yearsSacramento County38San Diego County: 38 yearsSan Diego County38Butte County: 37.9 yearsButte County37.9Riverside County: 37.8 yearsRiverside County37.8San Benito County: 37.6 yearsSan Benito County37.6Sutter County: 37.4 yearsSutter County37.4Monterey County: 36.5 yearsMonterey County36.5Colusa County: 36.3 yearsColusa County36.3San Joaquin County: 36.3 yearsSan Joaquin County36.3Stanislaus County: 36 yearsStanislaus County36San Bernardino County: 35.9 yearsSan Bernardino County35.9Santa Barbara County: 35.9 yearsSanta Barbara County35.9Yuba County: 35.2 yearsYuba County35.2Madera County: 35 yearsMadera County35Imperial County: 34.8 yearsImperial County34.8Fresno County: 34.3 yearsFresno County34.3Kern County: 33.7 yearsKern County33.7Kings County: 33.7 yearsKings County33.7Tulare County: 33.2 yearsTulare County33.2Merced County: 32.9 yearsMerced County32.9Yolo County: 32.2 yearsYolo County32.2Sierra County: 55.2 yearsSierra County55.2Plumas County: 52.6 yearsPlumas County52.6Alpine County: 51.4 yearsAlpine County51.4Amador County: 50.2 yearsAmador County50.2Calaveras County: 50.2 yearsCalaveras County50.2Trinity County: 49.8 yearsTrinity County49.8Nevada County: 49.3 yearsNevada County49.3Mariposa County: 49.2 yearsMariposa County49.2Modoc County: 48.6 yearsModoc County48.6Tuolumne County: 48.1 yearsTuolumne County48.1Marin County: 48 yearsMarin County48Siskiyou County: 48 yearsSiskiyou County48El Dorado County: 46.8 yearsEl Dorado County46.8Mendocino County: 45 yearsMendocino County45Inyo County: 44.9 yearsInyo County44.9Napa County: 44.4 yearsNapa County44.4Lake County: 44.1 yearsLake County44.1Sonoma County: 44.1 yearsSonoma County44.1Placer County: 42.7 yearsPlacer County42.7Shasta County: 42.4 yearsShasta County42.4San Luis Obispo County: 41.7 yearsSan Luis Obispo County41.7Santa Cruz County: 41.5 yearsSanta Cruz County41.5Contra Costa County: 41.4 yearsContra Costa County41.4Del Norte County: 41.4 yearsDel Norte County41.4Mono County: 41.4 yearsMono County41.4San Mateo County: 41.3 yearsSan Mateo County41.3Humboldt County: 41 yearsHumboldt County41Ventura County: 40.9 yearsVentura County40.9Orange County: 40.4 yearsOrange County40.4Tehama County: 40.4 yearsTehama County40.4Solano County: 40.1 yearsSolano County40.1San Francisco County: 40 yearsSan Francisco County40Alameda County: 39.6 yearsAlameda County39.6Los Angeles County: 39.1 yearsLos Angeles County39.1Lassen County: 38.7 yearsLassen County38.7Santa Clara County: 38.4 yearsSanta Clara County38.4Glenn County: 38 yearsGlenn County38Sacramento County: 38 yearsSacramento County38San Diego County: 38 yearsSan Diego County38Butte County: 37.9 yearsButte County37.9Riverside County: 37.8 yearsRiverside County37.8San Benito County: 37.6 yearsSan Benito County37.6Sutter County: 37.4 yearsSutter County37.4Monterey County: 36.5 yearsMonterey County36.5Colusa County: 36.3 yearsColusa County36.3San Joaquin County: 36.3 yearsSan Joaquin County36.3Stanislaus County: 36 yearsStanislaus County36San Bernardino County: 35.9 yearsSan Bernardino County35.9Santa Barbara County: 35.9 yearsSanta Barbara County35.9Yuba County: 35.2 yearsYuba County35.2Madera County: 35 yearsMadera County35Imperial County: 34.8 yearsImperial County34.8Fresno County: 34.3 yearsFresno County34.3Kern County: 33.7 yearsKern County33.7Kings County: 33.7 yearsKings County33.7Tulare County: 33.2 yearsTulare County33.2Merced County: 32.9 yearsMerced County32.9Yolo County: 32.2 yearsYolo County32.2
years. 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. Retrieved 2026-10-12.

Full ranking

RankCounties2025
years		Change on 2024
1Sierra County55.2+0.1
2Plumas County52.6-0.5
3Alpine County51.40
4Amador County50.2-0.4
4Calaveras County50.2-0.2
6Trinity County49.8+0.5
7Nevada County49.3+0.1
8Mariposa County49.2-0.6
9Modoc County48.6+0.2
10Tuolumne County48.1+0.4
11Marin County48+0.4
11Siskiyou County48-0.1
13El Dorado County46.8+0.4
14Mendocino County45+0.4
15Inyo County44.9+0.1
16Napa County44.4+0.2
17Lake County44.1+0.1
17Sonoma County44.1+0.3
19Placer County42.7+0.1
20Shasta County42.4+0.1
21San Luis Obispo County41.7+0.1
22Santa Cruz County41.5+0.4
23Contra Costa County41.4+0.4
23Del Norte County41.4+0.4
23Mono County41.4+0.3
26San Mateo County41.3+0.1
27Humboldt County41+0.4
28Ventura County40.9+0.3
29Orange County40.4+0.3
29Tehama County40.4+0.1
31Solano County40.1+0.3
32San Francisco County40+0.1
33Alameda County39.6+0.4
34Los Angeles County39.1+0.4
35Lassen County38.7+0.2
36Santa Clara County38.4+0.2
37Glenn County38+0.2
37Sacramento County38+0.2
37San Diego County38+0.2
40Butte County37.9+0.2
41Riverside County37.8+0.3
42San Benito County37.6+0.3
43Sutter County37.4+0.1
44Monterey County36.5+0.2
45Colusa County36.3+0.1
45San Joaquin County36.3+0.2
47Stanislaus County36+0.2
48San Bernardino County35.9+0.3
48Santa Barbara County35.9+0.1
50Yuba County35.2+0.3
51Madera County35+0.1
52Imperial County34.8+0.3
53Fresno County34.3+0.3
54Kern County33.7+0.3
54Kings County33.7+0.3
56Tulare County33.2+0.2
57Merced County32.9+0.4
58Yolo County32.2+0.1

Other periods

About this ranking

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.

Counties only: the county file has no state or national medians, and medians cannot be added up. A single-year estimate, unlike median_age, which for US places is a five-year American Community Survey estimate.

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: 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.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Census Bureau. (2026). 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 (Counties in California by median age on 1 July (US county estimates), 2025) [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: 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, Counties in California by median age on 1 July (US county estimates), 2025. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. 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. Counties in California by median age on 1 July (US county estimates), 2025. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties.

Harvard

U.S. Census Bureau (2026) 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, Counties in California by median age on 1 July (US county estimates), 2025 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_california_by_2025,
  author = {{U.S. Census Bureau}},
  title = {{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: Counties in California by median age on 1 July (US county estimates), 2025}},
  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/median-age-july-1-us-counties/california-counties. Publisher attribution: 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.},
}
RIS
TY  - DATA
AU  - U.S. Census Bureau
TI  - 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: Counties in California by median age on 1 July (US county estimates), 2025
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/median-age-july-1-us-counties/california-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties.
N1  - Publisher attribution: 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.
ER  -
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Questions

Which county has the highest median age on 1 July (US county estimates)?

Sierra County, with 55.2 years in 2025, according to the U.S. Census Bureau.

Which county has the lowest median age on 1 July (US county estimates)?

Yolo County, with 32.2 years in 2025.

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: 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. Retrieved 2026-10-12.

Median age on 1 July (US county estimates): other rankings

Counties in California: more rankings