Seniors will comprise more than 20% of U.S. residents in 2030, up from 15% in 2020. By 2034, older adults will outnumber children, according to Census Bureau projections.

Across the U.S., 52 million Americans are 65 years or older, according to the U.S. Census Bureau, and a quarter of them live in just three states: California, Florida, and Texas. By comparison, North Dakota, South Dakota, Vermont, Wyoming, and Alaska each have fewer than 150,000 senior residents. The size of a state’s senior population means a lot in terms of demand for resources like health care, affordable housing, assisted living, in-home and nursing care, and support services, and the quality and availability of those resources help determine where seniors migrate.

With baby boomers moving into old age, fewer babies being born, and longer life expectancies, the senior population of America is on a spectacular rise. The lengthening of the U.S. life expectancy has been particularly dramatic, rising to nearly 79 years from 68 years in 1950.

Stacker compiled a list of counties with the most seniors in California using data from the U.S. Census Bureau. Counties are ranked by the highest percentage of residents 65 years or older according to 2020 5-year estimates.

Keep reading to find out which counties have the most seniors in California.

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#58. Kings County

– Population aged 65 or older: 10.3%
– Population aged 18 and younger: 27.1%
– Median age: 32 years old
— Median age of males: 32.2 years old
— Median age of females: 31.5 years old
– Total population: 151,090 people

#57. Kern County

– Population aged 65 or older: 11%
– Population aged 18 and younger: 28.9%
– Median age: 31.9 years old
— Median age of males: 31.3 years old
— Median age of females: 32.5 years old
– Total population: 892,458 people

#56. Merced County

– Population aged 65 or older: 11.2%
– Population aged 18 and younger: 29.5%
– Median age: 31.2 years old
— Median age of males: 30.4 years old
— Median age of females: 32 years old
– Total population: 273,661 people

#55. Tulare County

– Population aged 65 or older: 11.4%
– Population aged 18 and younger: 30.8%
– Median age: 31.2 years old
— Median age of males: 30.5 years old
— Median age of females: 31.9 years old
– Total population: 463,955 people

#54. San Bernardino County

– Population aged 65 or older: 11.6%
– Population aged 18 and younger: 26.4%
– Median age: 33.6 years old
— Median age of males: 32.6 years old
— Median age of females: 34.7 years old
– Total population: 2,162,532 people

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#53. Fresno County

– Population aged 65 or older: 12.2%
– Population aged 18 and younger: 28.4%
– Median age: 32.4 years old
— Median age of males: 31.6 years old
— Median age of females: 33.3 years old
– Total population: 990,204 people

#52. Yuba County

– Population aged 65 or older: 12.4%
– Population aged 18 and younger: 27.5%
– Median age: 33 years old
— Median age of males: 32.3 years old
— Median age of females: 34 years old
– Total population: 77,524 people

#51. Yolo County

– Population aged 65 or older: 12.5%
– Population aged 18 and younger: 21.0%
– Median age: 31.1 years old
— Median age of males: 30.5 years old
— Median age of females: 31.8 years old
– Total population: 218,774 people

#50. San Benito County

– Population aged 65 or older: 12.7%
– Population aged 18 and younger: 25.7%
– Median age: 35.7 years old
— Median age of males: 35 years old
— Median age of females: 36.5 years old
– Total population: 61,547 people

#49. San Joaquin County

– Population aged 65 or older: 12.8%
– Population aged 18 and younger: 27.1%
– Median age: 34.4 years old
— Median age of males: 33.3 years old
— Median age of females: 35.6 years old
– Total population: 751,615 people

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#48. Imperial County

– Population aged 65 or older: 12.9%
– Population aged 18 and younger: 28.7%
– Median age: 32.5 years old
— Median age of males: 31.6 years old
— Median age of females: 33.6 years old
– Total population: 180,580 people

#47. Stanislaus County

– Population aged 65 or older: 13%
– Population aged 18 and younger: 27.1%
– Median age: 34.3 years old
— Median age of males: 33.1 years old
— Median age of females: 35.2 years old
– Total population: 546,235 people

#46. Santa Clara County

– Population aged 65 or older: 13.5%
– Population aged 18 and younger: 21.9%
– Median age: 37.2 years old
— Median age of males: 36.1 years old
— Median age of females: 38.4 years old
– Total population: 1,924,379 people

#45. Monterey County

– Population aged 65 or older: 13.6%
– Population aged 18 and younger: 26.2%
– Median age: 34.7 years old
— Median age of males: 34.2 years old
— Median age of females: 35.2 years old
– Total population: 432,977 people

#44. Los Angeles County

– Population aged 65 or older: 13.6%
– Population aged 18 and younger: 21.7%
– Median age: 36.7 years old
— Median age of males: 35.6 years old
— Median age of females: 37.9 years old
– Total population: 10,040,682 people

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#43. Alameda County

– Population aged 65 or older: 13.9%
– Population aged 18 and younger: 20.6%
– Median age: 37.8 years old
— Median age of males: 36.9 years old
— Median age of females: 38.6 years old
– Total population: 1,661,584 people

#42. Madera County

– Population aged 65 or older: 14%
– Population aged 18 and younger: 27.4%
– Median age: 34.1 years old
— Median age of males: 33.2 years old
— Median age of females: 34.9 years old
– Total population: 155,925 people

#41. San Diego County

– Population aged 65 or older: 14.1%
– Population aged 18 and younger: 21.6%
– Median age: 36.1 years old
— Median age of males: 34.8 years old
— Median age of females: 37.5 years old
– Total population: 3,323,970 people

#40. Sacramento County

– Population aged 65 or older: 14.1%
– Population aged 18 and younger: 23.7%
– Median age: 36.4 years old
— Median age of males: 35.2 years old
— Median age of females: 37.7 years old
– Total population: 1,537,948 people

#39. Lassen County

– Population aged 65 or older: 14.4%
– Population aged 18 and younger: 16.1%
– Median age: 36.8 years old
— Median age of males: 35 years old
— Median age of females: 44.2 years old
– Total population: 30,600 people

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#38. Riverside County

– Population aged 65 or older: 14.5%
– Population aged 18 and younger: 25.2%
– Median age: 35.8 years old
— Median age of males: 35 years old
— Median age of females: 36.7 years old
– Total population: 2,437,864 people

#37. Colusa County

– Population aged 65 or older: 14.6%
– Population aged 18 and younger: 27.3%
– Median age: 35.4 years old
— Median age of males: 34.5 years old
— Median age of females: 36.4 years old
– Total population: 21,491 people

#36. Orange County

– Population aged 65 or older: 14.8%
– Population aged 18 and younger: 22.0%
– Median age: 38.3 years old
— Median age of males: 36.9 years old
— Median age of females: 39.6 years old
– Total population: 3,170,345 people

#35. Santa Barbara County

– Population aged 65 or older: 15.3%
– Population aged 18 and younger: 22.3%
– Median age: 33.8 years old
— Median age of males: 33 years old
— Median age of females: 34.9 years old
– Total population: 444,895 people

#34. Mono County

– Population aged 65 or older: 15.3%
– Population aged 18 and younger: 20.7%
– Median age: 39.5 years old
— Median age of males: 38.3 years old
— Median age of females: 40.6 years old
– Total population: 14,395 people

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#33. Sutter County

– Population aged 65 or older: 15.4%
– Population aged 18 and younger: 25.9%
– Median age: 35.8 years old
— Median age of males: 34.7 years old
— Median age of females: 37.1 years old
– Total population: 96,315 people

#32. Ventura County

– Population aged 65 or older: 15.6%
– Population aged 18 and younger: 22.9%
– Median age: 38.5 years old
— Median age of males: 37.2 years old
— Median age of females: 39.9 years old
– Total population: 845,599 people

#31. Solano County

– Population aged 65 or older: 15.7%
– Population aged 18 and younger: 22.2%
– Median age: 38.3 years old
— Median age of males: 36.9 years old
— Median age of females: 40.1 years old
– Total population: 444,538 people

#30. San Francisco

– Population aged 65 or older: 15.8%
– Population aged 18 and younger: 13.4%
– Median age: 38.3 years old
— Median age of males: 37.9 years old
— Median age of females: 38.7 years old
– Total population: 874,784 people

#29. Contra Costa County

– Population aged 65 or older: 15.8%
– Population aged 18 and younger: 22.7%
– Median age: 39.9 years old
— Median age of males: 38.5 years old
— Median age of females: 41.1 years old
– Total population: 1,147,788 people

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#28. San Mateo County

– Population aged 65 or older: 16.2%
– Population aged 18 and younger: 20.5%
– Median age: 39.8 years old
— Median age of males: 38.4 years old
— Median age of females: 41.3 years old
– Total population: 765,623 people

#27. Glenn County

– Population aged 65 or older: 16.4%
– Population aged 18 and younger: 26.7%
– Median age: 35.9 years old
— Median age of males: 35 years old
— Median age of females: 37.4 years old
– Total population: 28,060 people

#26. Santa Cruz County

– Population aged 65 or older: 16.4%
– Population aged 18 and younger: 19.1%
– Median age: 38.2 years old
— Median age of males: 37.3 years old
— Median age of females: 39.3 years old
– Total population: 273,170 people

#25. Humboldt County

– Population aged 65 or older: 17.8%
– Population aged 18 and younger: 19.1%
– Median age: 38.9 years old
— Median age of males: 38.3 years old
— Median age of females: 39.5 years old
– Total population: 136,101 people

#24. Del Norte County

– Population aged 65 or older: 17.8%
– Population aged 18 and younger: 21.7%
– Median age: 40 years old
— Median age of males: 38.8 years old
— Median age of females: 42.1 years old
– Total population: 27,692 people

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#23. Butte County

– Population aged 65 or older: 18.2%
– Population aged 18 and younger: 20.1%
– Median age: 36.9 years old
— Median age of males: 35.6 years old
— Median age of females: 38.2 years old
– Total population: 223,344 people

#22. Napa County

– Population aged 65 or older: 19.2%
– Population aged 18 and younger: 20.6%
– Median age: 41.8 years old
— Median age of males: 40.8 years old
— Median age of females: 43 years old
– Total population: 138,572 people

#21. Placer County

– Population aged 65 or older: 19.6%
– Population aged 18 and younger: 22.2%
– Median age: 42.2 years old
— Median age of males: 40.7 years old
— Median age of females: 43.6 years old
– Total population: 391,799 people

#20. Sonoma County

– Population aged 65 or older: 19.6%
– Population aged 18 and younger: 19.6%
– Median age: 42.4 years old
— Median age of males: 40.9 years old
— Median age of females: 44 years old
– Total population: 496,801 people

#19. Tehama County

– Population aged 65 or older: 19.8%
– Population aged 18 and younger: 23.9%
– Median age: 40.6 years old
— Median age of males: 39.3 years old
— Median age of females: 42.3 years old
– Total population: 64,176 people

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#18. San Luis Obispo County

– Population aged 65 or older: 20.1%
– Population aged 18 and younger: 17.7%
– Median age: 39.5 years old
— Median age of males: 37.8 years old
— Median age of females: 41.6 years old
– Total population: 282,517 people

#17. Shasta County

– Population aged 65 or older: 20.6%
– Population aged 18 and younger: 21.6%
– Median age: 41.7 years old
— Median age of males: 39.9 years old
— Median age of females: 43.7 years old
– Total population: 179,267 people

#16. El Dorado County

– Population aged 65 or older: 21.2%
– Population aged 18 and younger: 19.9%
– Median age: 46.3 years old
— Median age of males: 45.2 years old
— Median age of females: 47.4 years old
– Total population: 190,345 people

#15. Mendocino County

– Population aged 65 or older: 22.1%
– Population aged 18 and younger: 21.3%
– Median age: 43.4 years old
— Median age of males: 42.2 years old
— Median age of females: 44.8 years old
– Total population: 87,110 people

#14. Marin County

– Population aged 65 or older: 22.3%
– Population aged 18 and younger: 20.0%
– Median age: 47.1 years old
— Median age of males: 45.6 years old
— Median age of females: 48.4 years old
– Total population: 259,441 people

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#13. Lake County

– Population aged 65 or older: 22.8%
– Population aged 18 and younger: 21.0%
– Median age: 45.3 years old
— Median age of males: 43.4 years old
— Median age of females: 47.1 years old
– Total population: 64,276 people

#12. Inyo County

– Population aged 65 or older: 23.3%
– Population aged 18 and younger: 20.8%
– Median age: 45.3 years old
— Median age of males: 43.9 years old
— Median age of females: 46.9 years old
– Total population: 17,930 people

#11. Siskiyou County

– Population aged 65 or older: 25.2%
– Population aged 18 and younger: 20.2%
– Median age: 47.7 years old
— Median age of males: 46.2 years old
— Median age of females: 49.4 years old
– Total population: 43,516 people

#10. Tuolumne County

– Population aged 65 or older: 26.1%
– Population aged 18 and younger: 16.6%
– Median age: 48.7 years old
— Median age of males: 45.4 years old
— Median age of females: 51.5 years old
– Total population: 54,147 people

#9. Amador County

– Population aged 65 or older: 27%
– Population aged 18 and younger: 15.3%
– Median age: 49.9 years old
— Median age of males: 47.2 years old
— Median age of females: 53.7 years old
– Total population: 39,023 people

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#8. Modoc County

– Population aged 65 or older: 27.4%
– Population aged 18 and younger: 19.7%
– Median age: 47.6 years old
— Median age of males: 46.9 years old
— Median age of females: 47.8 years old
– Total population: 8,853 people

#7. Nevada County

– Population aged 65 or older: 27.4%
– Population aged 18 and younger: 17.1%
– Median age: 50.5 years old
— Median age of males: 48.4 years old
— Median age of females: 52.7 years old
– Total population: 99,417 people

#6. Plumas County

– Population aged 65 or older: 27.7%
– Population aged 18 and younger: 16.8%
– Median age: 51.9 years old
— Median age of males: 51.8 years old
— Median age of females: 52.2 years old
– Total population: 18,844 people

#5. Trinity County

– Population aged 65 or older: 28%
– Population aged 18 and younger: 17.2%
– Median age: 52.4 years old
— Median age of males: 52.5 years old
— Median age of females: 52.3 years old
– Total population: 12,541 people

#4. Calaveras County

– Population aged 65 or older: 28%
– Population aged 18 and younger: 16.6%
– Median age: 52.8 years old
— Median age of males: 51 years old
— Median age of females: 53.7 years old
– Total population: 45,828 people

#3. Mariposa County

– Population aged 65 or older: 28.2%
– Population aged 18 and younger: 16.4%
– Median age: 51.8 years old
— Median age of males: 50.7 years old
— Median age of females: 53.6 years old
– Total population: 17,319 people

#2. Sierra County

– Population aged 65 or older: 28.2%
– Population aged 18 and younger: 15.3%
– Median age: 54 years old
— Median age of males: 49 years old
— Median age of females: 55.1 years old
– Total population: 2,898 people

#1. Alpine County

– Population aged 65 or older: 29.1%
– Population aged 18 and younger: 21.7%
– Median age: 47.6 years old
— Median age of males: 48.7 years old
— Median age of females: 42.3 years old
– Total population: 1,159 people