RANKING · 2024 ACS · 58 SHOWN OF 58

Oldest by median age, California counties

California counties ranked by median age of residents (2024 ACS). This list covers the 58 counties in California that qualify, ranked against each other statewide. The median across all 58 is 39.8. Biggest climber in the top 100 since 2020: Trinity County, CA, up 10 places to #1.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDLargest foreign-born population Most residents with a disability Largest veteran population Most uninsured people Largest senior population Most unmarried people

YEAR1990 2000 2010 2020 2024

RANKPLACESTATEPOPMEDIAN AGEVS 2000

01▲10Trinity County, CACA15,72054.9+23%

02▼1Sierra County, CACA3,09854.7+25%

03▲2Calaveras County, CACA46,60552.0+17%

04▼2Plumas County, CACA18,58352.0+18%

05▼2Mariposa County, CACA16,91851.2+19%

06▲1Nevada County, CACA101,91150.1+16%

07▼3Amador County, CACA41,87649.7+16%

08Tuolumne County, CACA53,16048.4+13%

09Modoc County, CACA8,42647.5+14%

10▲2Marin County, CACA253,69447.4+15%

11▼1Siskiyou County, CACA42,01347.2+10%

12▲1El Dorado County, CACA192,32346.1+17%

13▲2Inyo County, CACA18,15845.5+6%

14Lake County, CACA67,77244.1+3%

15▲1Mendocino County, CACA88,12244.1+13%

16▲1Napa County, CACA132,94942.9+12%

17▲2Sonoma County, CACA486,44442.9+14%

18▲2Placer County, CACA442,08142.5+12%

19▼1Shasta County, CACA181,64841.7+7%

20▲7Mono County, CACA12,50541.5+15%

21▲5San Mateo County, CACA743,56840.9+11%

22▲3Contra Costa County, CACA1,170,07040.5+11%

23▼2San Luis Obispo County, CACA282,36740.4+8%

24▲8San Francisco County, CACA826,07940.0+10%

25▼3Tehama County, CACA64,66540.0+6%

26▼3Del Norte County, CACA26,41039.9+10%

27▲2Humboldt County, CACA131,64739.9+10%

28▼22Alpine County, CACA1,04339.8+1%

29▼5Santa Cruz County, CACA258,85239.8+14%

30▼2Ventura County, CACA830,85139.6+16%

31▼1Orange County, CACA3,149,50739.4+18%

32▼1Solano County, CACA455,37639.2+16%

33▲1Alameda County, CACA1,636,63039.0+13%

34▲4Lassen County, CACA28,11738.3+11%

35▲1Los Angeles County, CACA9,694,93438.2+19%

36▲1Santa Clara County, CACA1,914,39138.1+12%

37▲3Sacramento County, CACA1,618,46037.5+11%

38▲1San Diego County, CACA3,282,24837.3+12%

39▲3Riverside County, CACA2,544,91637.0+12%

40▲1Sutter County, CACA98,78736.5+7%

41▼8Butte County, CACA209,21136.2+1%

42▼7Glenn County, CACA28,14136.2+7%

43San Benito County, CACA70,08236.1+15%

44▲1Colusa County, CACA21,83635.9+14%

45▲4Monterey County, CACA433,72935.5+12%

46▲1San Joaquin County, CACA823,81535.4+11%

47▼1Stanislaus County, CACA557,71934.9+10%

48▲2San Bernardino County, CACA2,224,09134.7+15%

49▼1Madera County, CACA167,92734.6+6%

50▼6Santa Barbara County, CACA442,06534.6+4%

51▲1Yuba County, CACA88,69134.2+9%

52▲1Fresno County, CACA1,035,45633.5+12%

53▼2Imperial County, CACA181,41133.2+7%

54▲2Kern County, CACA927,06832.7+7%

55Kings County, CACA154,32732.5+8%

56▲1Tulare County, CACA485,14632.1+10%

57▼3Yolo County, CACA224,41032.1+9%

58Merced County, CACA297,26031.8+10%

SHOWING 1–58 OF 58

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU ACS 5-YEAR ESTIMATES