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)

Sierra County had the highest median age on 1 July (US county estimates) of 58 counties in 2021, at 53.7 years. Merced County had the lowest, at 31.9 years. The median was 39.7 years. Source: the U.S. Census Bureau.

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Highest53.7Sierra County
Lowest31.9Merced County
Median39.758 counties

Map of counties, 2021

Alameda County: 38.4 yearsAlpine County: 51.1 yearsAmador County: 51.4 yearsButte County: 38.1 yearsCalaveras County: 51 yearsColusa County: 35.8 yearsContra Costa County: 40.3 yearsDel Norte County: 40.4 yearsEl Dorado County: 46 yearsFresno County: 33.4 yearsGlenn County: 37.8 yearsHumboldt County: 39.6 yearsImperial County: 34 yearsInyo County: 44.5 yearsKern County: 32.8 yearsKings County: 32.8 yearsLake County: 44.2 yearsLassen County: 37.3 yearsLos Angeles County: 38 yearsMadera County: 34.8 yearsMarin County: 46.8 yearsMariposa County: 51.7 yearsMendocino County: 43.4 yearsMerced County: 31.9 yearsModoc County: 49.7 yearsMono County: 40.2 yearsMonterey County: 35.3 yearsNapa County: 43 yearsNevada County: 49.3 yearsOrange County: 39.2 yearsPlacer County: 42.3 yearsPlumas County: 52.6 yearsRiverside County: 36.8 yearsSacramento County: 37.1 yearsSan Benito County: 36.6 yearsSan Bernardino County: 34.8 yearsSan Diego County: 37.3 yearsSan Francisco County: 39.7 yearsSan Joaquin County: 35.4 yearsSan Luis Obispo County: 41.8 yearsSan Mateo County: 40.6 yearsSanta Barbara County: 36.3 yearsSanta Clara County: 38.1 yearsSanta Cruz County: 41.3 yearsShasta County: 42.3 yearsSierra County: 53.7 yearsSiskiyou County: 48.3 yearsSolano County: 39.1 yearsSonoma County: 43 yearsStanislaus County: 35.4 yearsSutter County: 37.1 yearsTehama County: 40.5 yearsTrinity County: 47.7 yearsTulare County: 32.3 yearsTuolumne County: 48.8 yearsVentura County: 39.8 yearsYolo County: 33.6 yearsYuba County: 34.3 years
  • Under 35
  • 35 to 37
  • 37 to 40
  • 40 to 42
  • 42 to 48
  • 48 and over
years, 2021. 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, 2021

Sierra County: 53.7 yearsSierra County53.7Plumas County: 52.6 yearsPlumas County52.6Mariposa County: 51.7 yearsMariposa County51.7Amador County: 51.4 yearsAmador County51.4Alpine County: 51.1 yearsAlpine County51.1Calaveras County: 51 yearsCalaveras County51Modoc County: 49.7 yearsModoc County49.7Nevada County: 49.3 yearsNevada County49.3Tuolumne County: 48.8 yearsTuolumne County48.8Siskiyou County: 48.3 yearsSiskiyou County48.3Trinity County: 47.7 yearsTrinity County47.7Marin County: 46.8 yearsMarin County46.8El Dorado County: 46 yearsEl Dorado County46Inyo County: 44.5 yearsInyo County44.5Lake County: 44.2 yearsLake County44.2Mendocino County: 43.4 yearsMendocino County43.4Napa County: 43 yearsNapa County43Sonoma County: 43 yearsSonoma County43Placer County: 42.3 yearsPlacer County42.3Shasta County: 42.3 yearsShasta County42.3San Luis Obispo County: 41.8 yearsSan Luis Obispo County41.8Santa Cruz County: 41.3 yearsSanta Cruz County41.3San Mateo County: 40.6 yearsSan Mateo County40.6Tehama County: 40.5 yearsTehama County40.5Del Norte County: 40.4 yearsDel Norte County40.4Contra Costa County: 40.3 yearsContra Costa County40.3Mono County: 40.2 yearsMono County40.2Ventura County: 39.8 yearsVentura County39.8San Francisco County: 39.7 yearsSan Francisco County39.7Humboldt County: 39.6 yearsHumboldt County39.6Orange County: 39.2 yearsOrange County39.2Solano County: 39.1 yearsSolano County39.1Alameda County: 38.4 yearsAlameda County38.4Butte County: 38.1 yearsButte County38.1Santa Clara County: 38.1 yearsSanta Clara County38.1Los Angeles County: 38 yearsLos Angeles County38Glenn County: 37.8 yearsGlenn County37.8Lassen County: 37.3 yearsLassen County37.3San Diego County: 37.3 yearsSan Diego County37.3Sacramento County: 37.1 yearsSacramento County37.1Sutter County: 37.1 yearsSutter County37.1Riverside County: 36.8 yearsRiverside County36.8San Benito County: 36.6 yearsSan Benito County36.6Santa Barbara County: 36.3 yearsSanta Barbara County36.3Colusa County: 35.8 yearsColusa County35.8San Joaquin County: 35.4 yearsSan Joaquin County35.4Stanislaus County: 35.4 yearsStanislaus County35.4Monterey County: 35.3 yearsMonterey County35.3Madera County: 34.8 yearsMadera County34.8San Bernardino County: 34.8 yearsSan Bernardino County34.8Yuba County: 34.3 yearsYuba County34.3Imperial County: 34 yearsImperial County34Yolo County: 33.6 yearsYolo County33.6Fresno County: 33.4 yearsFresno County33.4Kern County: 32.8 yearsKern County32.8Kings County: 32.8 yearsKings County32.8Tulare County: 32.3 yearsTulare County32.3Merced County: 31.9 yearsMerced County31.9Sierra County: 53.7 yearsSierra County53.7Plumas County: 52.6 yearsPlumas County52.6Mariposa County: 51.7 yearsMariposa County51.7Amador County: 51.4 yearsAmador County51.4Alpine County: 51.1 yearsAlpine County51.1Calaveras County: 51 yearsCalaveras County51Modoc County: 49.7 yearsModoc County49.7Nevada County: 49.3 yearsNevada County49.3Tuolumne County: 48.8 yearsTuolumne County48.8Siskiyou County: 48.3 yearsSiskiyou County48.3Trinity County: 47.7 yearsTrinity County47.7Marin County: 46.8 yearsMarin County46.8El Dorado County: 46 yearsEl Dorado County46Inyo County: 44.5 yearsInyo County44.5Lake County: 44.2 yearsLake County44.2Mendocino County: 43.4 yearsMendocino County43.4Napa County: 43 yearsNapa County43Sonoma County: 43 yearsSonoma County43Placer County: 42.3 yearsPlacer County42.3Shasta County: 42.3 yearsShasta County42.3San Luis Obispo County: 41.8 yearsSan Luis Obispo County41.8Santa Cruz County: 41.3 yearsSanta Cruz County41.3San Mateo County: 40.6 yearsSan Mateo County40.6Tehama County: 40.5 yearsTehama County40.5Del Norte County: 40.4 yearsDel Norte County40.4Contra Costa County: 40.3 yearsContra Costa County40.3Mono County: 40.2 yearsMono County40.2Ventura County: 39.8 yearsVentura County39.8San Francisco County: 39.7 yearsSan Francisco County39.7Humboldt County: 39.6 yearsHumboldt County39.6Orange County: 39.2 yearsOrange County39.2Solano County: 39.1 yearsSolano County39.1Alameda County: 38.4 yearsAlameda County38.4Butte County: 38.1 yearsButte County38.1Santa Clara County: 38.1 yearsSanta Clara County38.1Los Angeles County: 38 yearsLos Angeles County38Glenn County: 37.8 yearsGlenn County37.8Lassen County: 37.3 yearsLassen County37.3San Diego County: 37.3 yearsSan Diego County37.3Sacramento County: 37.1 yearsSacramento County37.1Sutter County: 37.1 yearsSutter County37.1Riverside County: 36.8 yearsRiverside County36.8San Benito County: 36.6 yearsSan Benito County36.6Santa Barbara County: 36.3 yearsSanta Barbara County36.3Colusa County: 35.8 yearsColusa County35.8San Joaquin County: 35.4 yearsSan Joaquin County35.4Stanislaus County: 35.4 yearsStanislaus County35.4Monterey County: 35.3 yearsMonterey County35.3Madera County: 34.8 yearsMadera County34.8San Bernardino County: 34.8 yearsSan Bernardino County34.8Yuba County: 34.3 yearsYuba County34.3Imperial County: 34 yearsImperial County34Yolo County: 33.6 yearsYolo County33.6Fresno County: 33.4 yearsFresno County33.4Kern County: 32.8 yearsKern County32.8Kings County: 32.8 yearsKings County32.8Tulare County: 32.3 yearsTulare County32.3Merced County: 31.9 yearsMerced County31.9
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

RankCounties2021
years		Change on 2020
1Sierra County53.7-0.5
2Plumas County52.6-0.4
3Mariposa County51.7-0.3
4Amador County51.4-0.3
5Alpine County51.1-0.9
6Calaveras County51-0.6
7Modoc County49.7+0.6
8Nevada County49.3-0.4
9Tuolumne County48.8-0.1
10Siskiyou County48.3-0.2
11Trinity County47.7-0.3
12Marin County46.8+0.2
13El Dorado County46-0.4
14Inyo County44.5-0.3
15Lake County44.2-0.5
16Mendocino County43.4+0.2
17Napa County43+0.1
17Sonoma County43+0.4
19Placer County42.3-0.1
19Shasta County42.3-0.3
21San Luis Obispo County41.8+0.5
22Santa Cruz County41.3+1.4
23San Mateo County40.6+0.7
24Tehama County40.5+0.1
25Del Norte County40.40
26Contra Costa County40.3+0.2
27Mono County40.2+0.4
28Ventura County39.8+0.4
29San Francisco County39.7+1.6
30Humboldt County39.6+0.6
31Orange County39.2+0.4
32Solano County39.1+0.1
33Alameda County38.4+0.7
34Butte County38.1+0.3
34Santa Clara County38.1+0.6
36Los Angeles County38+0.6
37Glenn County37.8+0.3
38Lassen County37.30
38San Diego County37.3+0.4
40Sacramento County37.1+0.2
40Sutter County37.1+0.1
42Riverside County36.8+0.1
43San Benito County36.6-0.1
44Santa Barbara County36.3+0.9
45Colusa County35.8+0.3
46San Joaquin County35.4+0.1
46Stanislaus County35.4+0.1
48Monterey County35.3+0.4
49Madera County34.80
49San Bernardino County34.8+0.1
51Yuba County34.3+0.1
52Imperial County340
53Yolo County33.6+1
54Fresno County33.4+0.1
55Kern County32.8+0.1
55Kings County32.80
57Tulare County32.3+0.1
58Merced County31.9+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), 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: 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), 2021. 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?period=2021. 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), 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/median-age-july-1-us-counties/california-counties?period=2021.

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), 2021 [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?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: 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), 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/median-age-july-1-us-counties/california-counties?period=2021. 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), 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/median-age-july-1-us-counties/california-counties?period=2021
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties?period=2021.
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 53.7 years in 2021, according to the U.S. Census Bureau.

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

Merced County, with 31.9 years 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: 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