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 2020, at 54.2 years. Merced County had the lowest, at 31.8 years. The median was 39 years. Source: the U.S. Census Bureau.

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Highest54.2Sierra County
Lowest31.8Merced County
Median3958 counties

Map of counties, 2020

Alameda County: 37.7 yearsAlpine County: 52 yearsAmador County: 51.7 yearsButte County: 37.8 yearsCalaveras County: 51.6 yearsColusa County: 35.5 yearsContra Costa County: 40.1 yearsDel Norte County: 40.4 yearsEl Dorado County: 46.4 yearsFresno County: 33.3 yearsGlenn County: 37.5 yearsHumboldt County: 39 yearsImperial County: 34 yearsInyo County: 44.8 yearsKern County: 32.7 yearsKings County: 32.8 yearsLake County: 44.7 yearsLassen County: 37.3 yearsLos Angeles County: 37.4 yearsMadera County: 34.8 yearsMarin County: 46.6 yearsMariposa County: 52 yearsMendocino County: 43.2 yearsMerced County: 31.8 yearsModoc County: 49.1 yearsMono County: 39.8 yearsMonterey County: 34.9 yearsNapa County: 42.9 yearsNevada County: 49.7 yearsOrange County: 38.8 yearsPlacer County: 42.4 yearsPlumas County: 53 yearsRiverside County: 36.7 yearsSacramento County: 36.9 yearsSan Benito County: 36.7 yearsSan Bernardino County: 34.7 yearsSan Diego County: 36.9 yearsSan Francisco County: 38.1 yearsSan Joaquin County: 35.3 yearsSan Luis Obispo County: 41.3 yearsSan Mateo County: 39.9 yearsSanta Barbara County: 35.4 yearsSanta Clara County: 37.5 yearsSanta Cruz County: 39.9 yearsShasta County: 42.6 yearsSierra County: 54.2 yearsSiskiyou County: 48.5 yearsSolano County: 39 yearsSonoma County: 42.6 yearsStanislaus County: 35.3 yearsSutter County: 37 yearsTehama County: 40.4 yearsTrinity County: 48 yearsTulare County: 32.2 yearsTuolumne County: 48.9 yearsVentura County: 39.4 yearsYolo County: 32.6 yearsYuba County: 34.2 years
  • Under 35
  • 35 to 37
  • 37 to 39
  • 39 to 42
  • 42 to 48
  • 48 and over
years, 2020. 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, 2020

Sierra County: 54.2 yearsSierra County54.2Plumas County: 53 yearsPlumas County53Alpine County: 52 yearsAlpine County52Mariposa County: 52 yearsMariposa County52Amador County: 51.7 yearsAmador County51.7Calaveras County: 51.6 yearsCalaveras County51.6Nevada County: 49.7 yearsNevada County49.7Modoc County: 49.1 yearsModoc County49.1Tuolumne County: 48.9 yearsTuolumne County48.9Siskiyou County: 48.5 yearsSiskiyou County48.5Trinity County: 48 yearsTrinity County48Marin County: 46.6 yearsMarin County46.6El Dorado County: 46.4 yearsEl Dorado County46.4Inyo County: 44.8 yearsInyo County44.8Lake County: 44.7 yearsLake County44.7Mendocino County: 43.2 yearsMendocino County43.2Napa County: 42.9 yearsNapa County42.9Shasta County: 42.6 yearsShasta County42.6Sonoma County: 42.6 yearsSonoma County42.6Placer County: 42.4 yearsPlacer County42.4San Luis Obispo County: 41.3 yearsSan Luis Obispo County41.3Del Norte County: 40.4 yearsDel Norte County40.4Tehama County: 40.4 yearsTehama County40.4Contra Costa County: 40.1 yearsContra Costa County40.1San Mateo County: 39.9 yearsSan Mateo County39.9Santa Cruz County: 39.9 yearsSanta Cruz County39.9Mono County: 39.8 yearsMono County39.8Ventura County: 39.4 yearsVentura County39.4Humboldt County: 39 yearsHumboldt County39Solano County: 39 yearsSolano County39Orange County: 38.8 yearsOrange County38.8San Francisco County: 38.1 yearsSan Francisco County38.1Butte County: 37.8 yearsButte County37.8Alameda County: 37.7 yearsAlameda County37.7Glenn County: 37.5 yearsGlenn County37.5Santa Clara County: 37.5 yearsSanta Clara County37.5Los Angeles County: 37.4 yearsLos Angeles County37.4Lassen County: 37.3 yearsLassen County37.3Sutter County: 37 yearsSutter County37Sacramento County: 36.9 yearsSacramento County36.9San Diego County: 36.9 yearsSan Diego County36.9Riverside County: 36.7 yearsRiverside County36.7San Benito County: 36.7 yearsSan Benito County36.7Colusa County: 35.5 yearsColusa County35.5Santa Barbara County: 35.4 yearsSanta Barbara County35.4San Joaquin County: 35.3 yearsSan Joaquin County35.3Stanislaus County: 35.3 yearsStanislaus County35.3Monterey County: 34.9 yearsMonterey County34.9Madera County: 34.8 yearsMadera County34.8San Bernardino County: 34.7 yearsSan Bernardino County34.7Yuba County: 34.2 yearsYuba County34.2Imperial County: 34 yearsImperial County34Fresno County: 33.3 yearsFresno County33.3Kings County: 32.8 yearsKings County32.8Kern County: 32.7 yearsKern County32.7Yolo County: 32.6 yearsYolo County32.6Tulare County: 32.2 yearsTulare County32.2Merced County: 31.8 yearsMerced County31.8Sierra County: 54.2 yearsSierra County54.2Plumas County: 53 yearsPlumas County53Alpine County: 52 yearsAlpine County52Mariposa County: 52 yearsMariposa County52Amador County: 51.7 yearsAmador County51.7Calaveras County: 51.6 yearsCalaveras County51.6Nevada County: 49.7 yearsNevada County49.7Modoc County: 49.1 yearsModoc County49.1Tuolumne County: 48.9 yearsTuolumne County48.9Siskiyou County: 48.5 yearsSiskiyou County48.5Trinity County: 48 yearsTrinity County48Marin County: 46.6 yearsMarin County46.6El Dorado County: 46.4 yearsEl Dorado County46.4Inyo County: 44.8 yearsInyo County44.8Lake County: 44.7 yearsLake County44.7Mendocino County: 43.2 yearsMendocino County43.2Napa County: 42.9 yearsNapa County42.9Shasta County: 42.6 yearsShasta County42.6Sonoma County: 42.6 yearsSonoma County42.6Placer County: 42.4 yearsPlacer County42.4San Luis Obispo County: 41.3 yearsSan Luis Obispo County41.3Del Norte County: 40.4 yearsDel Norte County40.4Tehama County: 40.4 yearsTehama County40.4Contra Costa County: 40.1 yearsContra Costa County40.1San Mateo County: 39.9 yearsSan Mateo County39.9Santa Cruz County: 39.9 yearsSanta Cruz County39.9Mono County: 39.8 yearsMono County39.8Ventura County: 39.4 yearsVentura County39.4Humboldt County: 39 yearsHumboldt County39Solano County: 39 yearsSolano County39Orange County: 38.8 yearsOrange County38.8San Francisco County: 38.1 yearsSan Francisco County38.1Butte County: 37.8 yearsButte County37.8Alameda County: 37.7 yearsAlameda County37.7Glenn County: 37.5 yearsGlenn County37.5Santa Clara County: 37.5 yearsSanta Clara County37.5Los Angeles County: 37.4 yearsLos Angeles County37.4Lassen County: 37.3 yearsLassen County37.3Sutter County: 37 yearsSutter County37Sacramento County: 36.9 yearsSacramento County36.9San Diego County: 36.9 yearsSan Diego County36.9Riverside County: 36.7 yearsRiverside County36.7San Benito County: 36.7 yearsSan Benito County36.7Colusa County: 35.5 yearsColusa County35.5Santa Barbara County: 35.4 yearsSanta Barbara County35.4San Joaquin County: 35.3 yearsSan Joaquin County35.3Stanislaus County: 35.3 yearsStanislaus County35.3Monterey County: 34.9 yearsMonterey County34.9Madera County: 34.8 yearsMadera County34.8San Bernardino County: 34.7 yearsSan Bernardino County34.7Yuba County: 34.2 yearsYuba County34.2Imperial County: 34 yearsImperial County34Fresno County: 33.3 yearsFresno County33.3Kings County: 32.8 yearsKings County32.8Kern County: 32.7 yearsKern County32.7Yolo County: 32.6 yearsYolo County32.6Tulare County: 32.2 yearsTulare County32.2Merced County: 31.8 yearsMerced County31.8
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

RankCounties2020
years		Change on 2019
1Sierra County54.2-0.2
2Plumas County530
3Alpine County52+3.3
3Mariposa County52-0.3
5Amador County51.7+0.2
6Calaveras County51.6+0.1
7Nevada County49.7-0.1
8Modoc County49.1+1
9Tuolumne County48.9-0.1
10Siskiyou County48.5+0.1
11Trinity County48+0.1
12Marin County46.6+0.2
13El Dorado County46.4+0.1
14Inyo County44.8-0.3
15Lake County44.7-0.6
16Mendocino County43.2+0.1
17Napa County42.9+0.3
18Shasta County42.6-0.3
18Sonoma County42.6+0.2
20Placer County42.4+0.1
21San Luis Obispo County41.3+0.1
22Del Norte County40.4+0.3
22Tehama County40.40
24Contra Costa County40.1+0.3
25San Mateo County39.9+0.2
25Santa Cruz County39.9+0.2
27Mono County39.8+0.5
28Ventura County39.4+0.2
29Humboldt County39+0.1
29Solano County39+0.2
31Orange County38.80
32San Francisco County38.1+0.1
33Butte County37.8-0.1
34Alameda County37.7+0.2
35Glenn County37.5-0.2
35Santa Clara County37.5+0.2
37Los Angeles County37.4+0.1
38Lassen County37.3-0.1
39Sutter County37+0.2
40Sacramento County36.9+0.1
40San Diego County36.90
42Riverside County36.7+0.1
42San Benito County36.7+0.2
44Colusa County35.5+0.3
45Santa Barbara County35.4-0.1
46San Joaquin County35.3+0.1
46Stanislaus County35.30
48Monterey County34.9+0.1
49Madera County34.80
50San Bernardino County34.7+0.1
51Yuba County34.20
52Imperial County34-0.3
53Fresno County33.3+0.2
54Kings County32.80
55Kern County32.7+0.1
56Yolo County32.6-0.4
57Tulare County32.2+0.1
58Merced County31.80

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), 2020) [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), 2020. 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=2020. 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), 2020. 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=2020.

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), 2020 [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=2020 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_california_by_2020,
  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), 2020}},
  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=2020. 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), 2020
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=2020
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties?period=2020.
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 54.2 years in 2020, according to the U.S. Census Bureau.

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

Merced County, with 31.8 years in 2020.

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