Ranking of California Counties By Population Aged 25 years and above with an Educational attainment of Less than High School Diploma in 2021 (ACS-5Yrs)
Updated on September 3, 2025.
Based on the US Census ACS-5Yrs estimates, in 2021, the population of California (aged 25 years and above) who had an educational attainment of Less than High School Diploma was 4,236,035. Among all California counties, Los Angeles County had the highest population (aged 25 years and above) with an educational attainment of Less than High School Diploma (1,381,447), followed by Orange County (294,180), and Riverside County (267,525).
The chart below shows the top 10 California counties, and the table below shows the ranking of all California counties.
You can see similar information for other educational attainments.
You can also see similar information for other states and for the United States.
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Related Topics: California ACS-5Yrs Estimates, 2021 Topic List.
Data Source: US Census - ACS 5-Year Estimates.
Ranking of California Counties By Population (Aged 25yrs+) with an Educational Attainment of Less than High School Diploma in 2021
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| Rank | County | Number of People |
|---|---|---|
| 1 | Los Angeles County | 1381447 |
| 2 | Orange County | 294180 |
| 3 | Riverside County | 267525 |
| 4 | San Diego County | 263063 |
| 5 | San Bernardino County | 260315 |
| 6 | Santa Clara County | 145904 |
| 7 | Fresno County | 136835 |
| 8 | Kern County | 132826 |
| 9 | Alameda County | 131272 |
| 10 | Sacramento County | 127455 |
| 11 | San Joaquin County | 96216 |
| 12 | Ventura County | 82625 |
| 13 | Contra Costa County | 82564 |
| 14 | San Francisco County | 77300 |
| 15 | Tulare County | 76249 |
| 16 | Monterey County | 75771 |
| 17 | Stanislaus County | 69960 |
| 18 | San Mateo County | 50652 |
| 19 | Santa Barbara County | 50274 |
| 20 | Merced County | 49054 |
| 21 | Sonoma County | 38619 |
| 22 | Solano County | 34837 |
| 23 | Imperial County | 32595 |
| 24 | Madera County | 27789 |
| 25 | Kings County | 24856 |
| 26 | Santa Cruz County | 21102 |
| 27 | Yolo County | 15832 |
| 28 | San Luis Obispo County | 15354 |
| 29 | Placer County | 14584 |
| 30 | Napa County | 14541 |
| 31 | Butte County | 13734 |
| 32 | Sutter County | 13202 |
| 33 | Marin County | 12672 |
| 34 | Shasta County | 11492 |
| 35 | Yuba County | 9568 |
| 36 | Mendocino County | 8704 |
| 37 | Humboldt County | 8451 |
| 38 | El Dorado County | 7421 |
| 39 | San Benito County | 6901 |
| 40 | Lake County | 6548 |
| 41 | Tehama County | 6389 |
| 42 | Lassen County | 4853 |
| 43 | Glenn County | 4303 |
| 44 | Nevada County | 3827 |
| 45 | Del Norte County | 3825 |
| 46 | Colusa County | 3719 |
| 47 | Tuolumne County | 3344 |
| 48 | Siskiyou County | 3250 |
| 49 | Calaveras County | 3214 |
| 50 | Amador County | 2757 |
| 51 | Mariposa County | 1233 |
| 52 | Mono County | 1214 |
| 53 | Inyo County | 1088 |
| 54 | Modoc County | 955 |
| 55 | Plumas County | 820 |
| 56 | Trinity County | 764 |
| 57 | Sierra County | 130 |
| 58 | Alpine County | 61 |