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 2017, at 54.5 years. Merced County had the lowest, at 31.3 years. The median was 38.3 years. Source: the U.S. Census Bureau.

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Highest54.5Sierra County
Lowest31.3Merced County
Median38.358 counties

Map of counties, 2017

Alameda County: 37.2 yearsAlpine County: 49.7 yearsAmador County: 51.4 yearsButte County: 38 yearsCalaveras County: 51.5 yearsColusa County: 34.7 yearsContra Costa County: 39.4 yearsDel Norte County: 39.8 yearsEl Dorado County: 46.1 yearsFresno County: 32.5 yearsGlenn County: 37.4 yearsHumboldt County: 38.2 yearsImperial County: 33.6 yearsInyo County: 45.7 yearsKern County: 32.1 yearsKings County: 32.2 yearsLake County: 46 yearsLassen County: 37.3 yearsLos Angeles County: 36.6 yearsMadera County: 34.4 yearsMarin County: 46.1 yearsMariposa County: 52.3 yearsMendocino County: 42.8 yearsMerced County: 31.3 yearsModoc County: 48.2 yearsMono County: 38.8 yearsMonterey County: 34.3 yearsNapa County: 41.8 yearsNevada County: 49.6 yearsOrange County: 38.1 yearsPlacer County: 42.1 yearsPlumas County: 52.9 yearsRiverside County: 35.8 yearsSacramento County: 36.3 yearsSan Benito County: 36.1 yearsSan Bernardino County: 33.9 yearsSan Diego County: 36.2 yearsSan Francisco County: 37.9 yearsSan Joaquin County: 34.7 yearsSan Luis Obispo County: 40.6 yearsSan Mateo County: 39.5 yearsSanta Barbara County: 34.9 yearsSanta Clara County: 37 yearsSanta Cruz County: 38.9 yearsShasta County: 43 yearsSierra County: 54.5 yearsSiskiyou County: 47.7 yearsSolano County: 38.3 yearsSonoma County: 41.8 yearsStanislaus County: 34.8 yearsSutter County: 36.4 yearsTehama County: 40.6 yearsTrinity County: 49 yearsTulare County: 31.5 yearsTuolumne County: 49 yearsVentura County: 38.4 yearsYolo County: 32.2 yearsYuba County: 33.6 years
  • Under 34
  • 34 to 36
  • 36 to 38
  • 38 to 42
  • 42 to 48
  • 48 and over
years, 2017. 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, 2017

Sierra County: 54.5 yearsSierra County54.5Plumas County: 52.9 yearsPlumas County52.9Mariposa County: 52.3 yearsMariposa County52.3Calaveras County: 51.5 yearsCalaveras County51.5Amador County: 51.4 yearsAmador County51.4Alpine County: 49.7 yearsAlpine County49.7Nevada County: 49.6 yearsNevada County49.6Trinity County: 49 yearsTrinity County49Tuolumne County: 49 yearsTuolumne County49Modoc County: 48.2 yearsModoc County48.2Siskiyou County: 47.7 yearsSiskiyou County47.7El Dorado County: 46.1 yearsEl Dorado County46.1Marin County: 46.1 yearsMarin County46.1Lake County: 46 yearsLake County46Inyo County: 45.7 yearsInyo County45.7Shasta County: 43 yearsShasta County43Mendocino County: 42.8 yearsMendocino County42.8Placer County: 42.1 yearsPlacer County42.1Napa County: 41.8 yearsNapa County41.8Sonoma County: 41.8 yearsSonoma County41.8San Luis Obispo County: 40.6 yearsSan Luis Obispo County40.6Tehama County: 40.6 yearsTehama County40.6Del Norte County: 39.8 yearsDel Norte County39.8San Mateo County: 39.5 yearsSan Mateo County39.5Contra Costa County: 39.4 yearsContra Costa County39.4Santa Cruz County: 38.9 yearsSanta Cruz County38.9Mono County: 38.8 yearsMono County38.8Ventura County: 38.4 yearsVentura County38.4Solano County: 38.3 yearsSolano County38.3Humboldt County: 38.2 yearsHumboldt County38.2Orange County: 38.1 yearsOrange County38.1Butte County: 38 yearsButte County38San Francisco County: 37.9 yearsSan Francisco County37.9Glenn County: 37.4 yearsGlenn County37.4Lassen County: 37.3 yearsLassen County37.3Alameda County: 37.2 yearsAlameda County37.2Santa Clara County: 37 yearsSanta Clara County37Los Angeles County: 36.6 yearsLos Angeles County36.6Sutter County: 36.4 yearsSutter County36.4Sacramento County: 36.3 yearsSacramento County36.3San Diego County: 36.2 yearsSan Diego County36.2San Benito County: 36.1 yearsSan Benito County36.1Riverside County: 35.8 yearsRiverside County35.8Santa Barbara County: 34.9 yearsSanta Barbara County34.9Stanislaus County: 34.8 yearsStanislaus County34.8Colusa County: 34.7 yearsColusa County34.7San Joaquin County: 34.7 yearsSan Joaquin County34.7Madera County: 34.4 yearsMadera County34.4Monterey County: 34.3 yearsMonterey County34.3San Bernardino County: 33.9 yearsSan Bernardino County33.9Imperial County: 33.6 yearsImperial County33.6Yuba County: 33.6 yearsYuba County33.6Fresno County: 32.5 yearsFresno County32.5Kings County: 32.2 yearsKings County32.2Yolo County: 32.2 yearsYolo County32.2Kern County: 32.1 yearsKern County32.1Tulare County: 31.5 yearsTulare County31.5Merced County: 31.3 yearsMerced County31.3Sierra County: 54.5 yearsSierra County54.5Plumas County: 52.9 yearsPlumas County52.9Mariposa County: 52.3 yearsMariposa County52.3Calaveras County: 51.5 yearsCalaveras County51.5Amador County: 51.4 yearsAmador County51.4Alpine County: 49.7 yearsAlpine County49.7Nevada County: 49.6 yearsNevada County49.6Trinity County: 49 yearsTrinity County49Tuolumne County: 49 yearsTuolumne County49Modoc County: 48.2 yearsModoc County48.2Siskiyou County: 47.7 yearsSiskiyou County47.7El Dorado County: 46.1 yearsEl Dorado County46.1Marin County: 46.1 yearsMarin County46.1Lake County: 46 yearsLake County46Inyo County: 45.7 yearsInyo County45.7Shasta County: 43 yearsShasta County43Mendocino County: 42.8 yearsMendocino County42.8Placer County: 42.1 yearsPlacer County42.1Napa County: 41.8 yearsNapa County41.8Sonoma County: 41.8 yearsSonoma County41.8San Luis Obispo County: 40.6 yearsSan Luis Obispo County40.6Tehama County: 40.6 yearsTehama County40.6Del Norte County: 39.8 yearsDel Norte County39.8San Mateo County: 39.5 yearsSan Mateo County39.5Contra Costa County: 39.4 yearsContra Costa County39.4Santa Cruz County: 38.9 yearsSanta Cruz County38.9Mono County: 38.8 yearsMono County38.8Ventura County: 38.4 yearsVentura County38.4Solano County: 38.3 yearsSolano County38.3Humboldt County: 38.2 yearsHumboldt County38.2Orange County: 38.1 yearsOrange County38.1Butte County: 38 yearsButte County38San Francisco County: 37.9 yearsSan Francisco County37.9Glenn County: 37.4 yearsGlenn County37.4Lassen County: 37.3 yearsLassen County37.3Alameda County: 37.2 yearsAlameda County37.2Santa Clara County: 37 yearsSanta Clara County37Los Angeles County: 36.6 yearsLos Angeles County36.6Sutter County: 36.4 yearsSutter County36.4Sacramento County: 36.3 yearsSacramento County36.3San Diego County: 36.2 yearsSan Diego County36.2San Benito County: 36.1 yearsSan Benito County36.1Riverside County: 35.8 yearsRiverside County35.8Santa Barbara County: 34.9 yearsSanta Barbara County34.9Stanislaus County: 34.8 yearsStanislaus County34.8Colusa County: 34.7 yearsColusa County34.7San Joaquin County: 34.7 yearsSan Joaquin County34.7Madera County: 34.4 yearsMadera County34.4Monterey County: 34.3 yearsMonterey County34.3San Bernardino County: 33.9 yearsSan Bernardino County33.9Imperial County: 33.6 yearsImperial County33.6Yuba County: 33.6 yearsYuba County33.6Fresno County: 32.5 yearsFresno County32.5Kings County: 32.2 yearsKings County32.2Yolo County: 32.2 yearsYolo County32.2Kern County: 32.1 yearsKern County32.1Tulare County: 31.5 yearsTulare County31.5Merced County: 31.3 yearsMerced County31.3
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

RankCounties2017
years		Change on 2016
1Sierra County54.5-0.1
2Plumas County52.9+0.2
3Mariposa County52.3+0.2
4Calaveras County51.5-0.2
5Amador County51.4-0.2
6Alpine County49.7-1.8
7Nevada County49.60
8Trinity County49-0.5
8Tuolumne County49-0.2
10Modoc County48.2+0.3
11Siskiyou County47.7-0.1
12El Dorado County46.1+0.2
12Marin County46.1+0.3
14Lake County46-0.2
15Inyo County45.7-0.1
16Shasta County43-0.1
17Mendocino County42.8+0.1
18Placer County42.1+0.1
19Napa County41.8+0.3
19Sonoma County41.8+0.3
21San Luis Obispo County40.6+0.4
21Tehama County40.60
23Del Norte County39.80
24San Mateo County39.5+0.1
25Contra Costa County39.4+0.1
26Santa Cruz County38.9+0.4
27Mono County38.8-0.2
28Ventura County38.4+0.3
29Solano County38.3+0.3
30Humboldt County38.2+0.3
31Orange County38.1+0.2
32Butte County38+0.2
33San Francisco County37.9-0.1
34Glenn County37.4+0.2
35Lassen County37.3-0.1
36Alameda County37.2+0.2
37Santa Clara County37+0.1
38Los Angeles County36.6+0.2
39Sutter County36.4+0.2
40Sacramento County36.3+0.2
41San Diego County36.2+0.3
42San Benito County36.1+0.1
43Riverside County35.8+0.3
44Santa Barbara County34.9+0.3
45Stanislaus County34.8+0.2
46Colusa County34.7-0.1
46San Joaquin County34.7+0.2
48Madera County34.4+0.2
49Monterey County34.3+0.3
50San Bernardino County33.9+0.3
51Imperial County33.6+0.3
51Yuba County33.6+0.1
53Fresno County32.5+0.3
54Kings County32.2+0.1
54Yolo County32.2+0.2
56Kern County32.1+0.3
57Tulare County31.5+0.2
58Merced County31.3+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), 2017) [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), 2017. 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=2017. 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), 2017. 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=2017.

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), 2017 [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=2017 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_california_by_2017,
  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), 2017}},
  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=2017. 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), 2017
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=2017
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/california-counties?period=2017.
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 2017, according to the U.S. Census Bureau.

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

Merced County, with 31.3 years in 2017.

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