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 2018, at 54.5 years. Merced County had the lowest, at 31.6 years. The median was 38.5 years. Source: the U.S. Census Bureau.

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Highest54.5Sierra County
Lowest31.6Merced County
Median38.558 counties

Map of counties, 2018

Alameda County: 37.4 yearsAlpine County: 51.5 yearsAmador County: 51.3 yearsButte County: 38.2 yearsCalaveras County: 51.6 yearsColusa County: 35 yearsContra Costa County: 39.6 yearsDel Norte County: 39.8 yearsEl Dorado County: 46.2 yearsFresno County: 32.8 yearsGlenn County: 37.4 yearsHumboldt County: 38.5 yearsImperial County: 33.9 yearsInyo County: 45.4 yearsKern County: 32.4 yearsKings County: 32.5 yearsLake County: 45.6 yearsLassen County: 37.4 yearsLos Angeles County: 37 yearsMadera County: 34.5 yearsMarin County: 46.2 yearsMariposa County: 52.1 yearsMendocino County: 42.9 yearsMerced County: 31.6 yearsModoc County: 48.6 yearsMono County: 39.1 yearsMonterey County: 34.6 yearsNapa County: 42.2 yearsNevada County: 49.7 yearsOrange County: 38.4 yearsPlacer County: 42.1 yearsPlumas County: 52.9 yearsRiverside County: 36.2 yearsSacramento County: 36.5 yearsSan Benito County: 36.3 yearsSan Bernardino County: 34.2 yearsSan Diego County: 36.5 yearsSan Francisco County: 38 yearsSan Joaquin County: 34.9 yearsSan Luis Obispo County: 40.8 yearsSan Mateo County: 39.6 yearsSanta Barbara County: 35.2 yearsSanta Clara County: 37.1 yearsSanta Cruz County: 39.3 yearsShasta County: 43 yearsSierra County: 54.5 yearsSiskiyou County: 48.1 yearsSolano County: 38.5 yearsSonoma County: 42.1 yearsStanislaus County: 35 yearsSutter County: 36.5 yearsTehama County: 40.5 yearsTrinity County: 48.5 yearsTulare County: 31.8 yearsTuolumne County: 48.9 yearsVentura County: 38.8 yearsYolo County: 32.6 yearsYuba County: 33.9 years
  • Under 35
  • 35 to 37
  • 37 to 39
  • 39 to 42
  • 42 to 48
  • 48 and over
years, 2018. 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, 2018

Sierra County: 54.5 yearsSierra County54.5Plumas County: 52.9 yearsPlumas County52.9Mariposa County: 52.1 yearsMariposa County52.1Calaveras County: 51.6 yearsCalaveras County51.6Alpine County: 51.5 yearsAlpine County51.5Amador County: 51.3 yearsAmador County51.3Nevada County: 49.7 yearsNevada County49.7Tuolumne County: 48.9 yearsTuolumne County48.9Modoc County: 48.6 yearsModoc County48.6Trinity County: 48.5 yearsTrinity County48.5Siskiyou County: 48.1 yearsSiskiyou County48.1El Dorado County: 46.2 yearsEl Dorado County46.2Marin County: 46.2 yearsMarin County46.2Lake County: 45.6 yearsLake County45.6Inyo County: 45.4 yearsInyo County45.4Shasta County: 43 yearsShasta County43Mendocino County: 42.9 yearsMendocino County42.9Napa County: 42.2 yearsNapa County42.2Placer County: 42.1 yearsPlacer County42.1Sonoma County: 42.1 yearsSonoma County42.1San Luis Obispo County: 40.8 yearsSan Luis Obispo County40.8Tehama County: 40.5 yearsTehama County40.5Del Norte County: 39.8 yearsDel Norte County39.8Contra Costa County: 39.6 yearsContra Costa County39.6San Mateo County: 39.6 yearsSan Mateo County39.6Santa Cruz County: 39.3 yearsSanta Cruz County39.3Mono County: 39.1 yearsMono County39.1Ventura County: 38.8 yearsVentura County38.8Humboldt County: 38.5 yearsHumboldt County38.5Solano County: 38.5 yearsSolano County38.5Orange County: 38.4 yearsOrange County38.4Butte County: 38.2 yearsButte County38.2San Francisco County: 38 yearsSan Francisco County38Alameda County: 37.4 yearsAlameda County37.4Glenn County: 37.4 yearsGlenn County37.4Lassen County: 37.4 yearsLassen County37.4Santa Clara County: 37.1 yearsSanta Clara County37.1Los Angeles County: 37 yearsLos Angeles County37Sacramento County: 36.5 yearsSacramento County36.5San Diego County: 36.5 yearsSan Diego County36.5Sutter County: 36.5 yearsSutter County36.5San Benito County: 36.3 yearsSan Benito County36.3Riverside County: 36.2 yearsRiverside County36.2Santa Barbara County: 35.2 yearsSanta Barbara County35.2Colusa County: 35 yearsColusa County35Stanislaus County: 35 yearsStanislaus County35San Joaquin County: 34.9 yearsSan Joaquin County34.9Monterey County: 34.6 yearsMonterey County34.6Madera County: 34.5 yearsMadera County34.5San Bernardino County: 34.2 yearsSan Bernardino County34.2Imperial County: 33.9 yearsImperial County33.9Yuba County: 33.9 yearsYuba County33.9Fresno County: 32.8 yearsFresno County32.8Yolo County: 32.6 yearsYolo County32.6Kings County: 32.5 yearsKings County32.5Kern County: 32.4 yearsKern County32.4Tulare County: 31.8 yearsTulare County31.8Merced County: 31.6 yearsMerced County31.6Sierra County: 54.5 yearsSierra County54.5Plumas County: 52.9 yearsPlumas County52.9Mariposa County: 52.1 yearsMariposa County52.1Calaveras County: 51.6 yearsCalaveras County51.6Alpine County: 51.5 yearsAlpine County51.5Amador County: 51.3 yearsAmador County51.3Nevada County: 49.7 yearsNevada County49.7Tuolumne County: 48.9 yearsTuolumne County48.9Modoc County: 48.6 yearsModoc County48.6Trinity County: 48.5 yearsTrinity County48.5Siskiyou County: 48.1 yearsSiskiyou County48.1El Dorado County: 46.2 yearsEl Dorado County46.2Marin County: 46.2 yearsMarin County46.2Lake County: 45.6 yearsLake County45.6Inyo County: 45.4 yearsInyo County45.4Shasta County: 43 yearsShasta County43Mendocino County: 42.9 yearsMendocino County42.9Napa County: 42.2 yearsNapa County42.2Placer County: 42.1 yearsPlacer County42.1Sonoma County: 42.1 yearsSonoma County42.1San Luis Obispo County: 40.8 yearsSan Luis Obispo County40.8Tehama County: 40.5 yearsTehama County40.5Del Norte County: 39.8 yearsDel Norte County39.8Contra Costa County: 39.6 yearsContra Costa County39.6San Mateo County: 39.6 yearsSan Mateo County39.6Santa Cruz County: 39.3 yearsSanta Cruz County39.3Mono County: 39.1 yearsMono County39.1Ventura County: 38.8 yearsVentura County38.8Humboldt County: 38.5 yearsHumboldt County38.5Solano County: 38.5 yearsSolano County38.5Orange County: 38.4 yearsOrange County38.4Butte County: 38.2 yearsButte County38.2San Francisco County: 38 yearsSan Francisco County38Alameda County: 37.4 yearsAlameda County37.4Glenn County: 37.4 yearsGlenn County37.4Lassen County: 37.4 yearsLassen County37.4Santa Clara County: 37.1 yearsSanta Clara County37.1Los Angeles County: 37 yearsLos Angeles County37Sacramento County: 36.5 yearsSacramento County36.5San Diego County: 36.5 yearsSan Diego County36.5Sutter County: 36.5 yearsSutter County36.5San Benito County: 36.3 yearsSan Benito County36.3Riverside County: 36.2 yearsRiverside County36.2Santa Barbara County: 35.2 yearsSanta Barbara County35.2Colusa County: 35 yearsColusa County35Stanislaus County: 35 yearsStanislaus County35San Joaquin County: 34.9 yearsSan Joaquin County34.9Monterey County: 34.6 yearsMonterey County34.6Madera County: 34.5 yearsMadera County34.5San Bernardino County: 34.2 yearsSan Bernardino County34.2Imperial County: 33.9 yearsImperial County33.9Yuba County: 33.9 yearsYuba County33.9Fresno County: 32.8 yearsFresno County32.8Yolo County: 32.6 yearsYolo County32.6Kings County: 32.5 yearsKings County32.5Kern County: 32.4 yearsKern County32.4Tulare County: 31.8 yearsTulare County31.8Merced County: 31.6 yearsMerced County31.6
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

RankCounties2018
years		Change on 2017
1Sierra County54.50
2Plumas County52.90
3Mariposa County52.1-0.2
4Calaveras County51.6+0.1
5Alpine County51.5+1.8
6Amador County51.3-0.1
7Nevada County49.7+0.1
8Tuolumne County48.9-0.1
9Modoc County48.6+0.4
10Trinity County48.5-0.5
11Siskiyou County48.1+0.4
12El Dorado County46.2+0.1
12Marin County46.2+0.1
14Lake County45.6-0.4
15Inyo County45.4-0.3
16Shasta County430
17Mendocino County42.9+0.1
18Napa County42.2+0.4
19Placer County42.10
19Sonoma County42.1+0.3
21San Luis Obispo County40.8+0.2
22Tehama County40.5-0.1
23Del Norte County39.80
24Contra Costa County39.6+0.2
24San Mateo County39.6+0.1
26Santa Cruz County39.3+0.4
27Mono County39.1+0.3
28Ventura County38.8+0.4
29Humboldt County38.5+0.3
29Solano County38.5+0.2
31Orange County38.4+0.3
32Butte County38.2+0.2
33San Francisco County38+0.1
34Alameda County37.4+0.2
34Glenn County37.40
34Lassen County37.4+0.1
37Santa Clara County37.1+0.1
38Los Angeles County37+0.4
39Sacramento County36.5+0.2
39San Diego County36.5+0.3
39Sutter County36.5+0.1
42San Benito County36.3+0.2
43Riverside County36.2+0.4
44Santa Barbara County35.2+0.3
45Colusa County35+0.3
45Stanislaus County35+0.2
47San Joaquin County34.9+0.2
48Monterey County34.6+0.3
49Madera County34.5+0.1
50San Bernardino County34.2+0.3
51Imperial County33.9+0.3
51Yuba County33.9+0.3
53Fresno County32.8+0.3
54Yolo County32.6+0.4
55Kings County32.5+0.3
56Kern County32.4+0.3
57Tulare County31.8+0.3
58Merced County31.6+0.3

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), 2018) [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), 2018. 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=2018. 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), 2018. 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=2018.

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), 2018 [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=2018 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_california_by_2018,
  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), 2018}},
  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=2018. 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), 2018
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=2018
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties?period=2018.
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 54.5 years in 2018, according to the U.S. Census Bureau.

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

Merced County, with 31.6 years in 2018.

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