Ranking of California Counties By Percentage of 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 percentage of the population of California (aged 25 years and above) who had an educational attainment of Less than High School Diploma was 15.81%. Among all California counties, Merced County had the highest percentage of its population (aged 25 years and above) with an educational attainment of Less than High School Diploma (29.65%), followed by Imperial County (29.56%), and Madera County (28.19%).
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 Percentage of Population (Aged 25yrs+) with an Educational Attainment of Less than High School Diploma in 2021
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| Rank | County | Percentage of Population (Aged 25yrs+) (%) |
|---|---|---|
| 1 | Merced County | 29.65 |
| 2 | Imperial County | 29.56 |
| 3 | Madera County | 28.19 |
| 4 | Tulare County | 27.38 |
| 5 | Monterey County | 27.01 |
| 6 | Colusa County | 26.68 |
| 7 | Kings County | 26.37 |
| 8 | Kern County | 24.05 |
| 9 | Glenn County | 23.52 |
| 10 | Fresno County | 22.09 |
| 11 | Sutter County | 20.35 |
| 12 | Stanislaus County | 20.05 |
| 13 | Los Angeles County | 19.96 |
| 14 | Lassen County | 19.95 |
| 15 | San Joaquin County | 19.70 |
| 16 | Del Norte County | 19.41 |
| 17 | San Bernardino County | 18.90 |
| 18 | Yuba County | 18.83 |
| 19 | Santa Barbara County | 18.09 |
| 20 | Riverside County | 17.01 |
| 21 | San Benito County | 16.75 |
| 22 | Napa County | 14.76 |
| 23 | Modoc County | 14.55 |
| 24 | Ventura County | 14.38 |
| 25 | Tehama County | 14.23 |
| 26 | Lake County | 13.41 |
| 27 | Orange County | 13.39 |
| 28 | Mendocino County | 13.36 |
| 29 | Mono County | 12.78 |
| 30 | Yolo County | 12.40 |
| 31 | Sacramento County | 11.94 |
| 32 | Santa Cruz County | 11.72 |
| 33 | San Diego County | 11.69 |
| 34 | San Francisco County | 11.22 |
| 35 | Solano County | 11.15 |
| 36 | Alameda County | 11.00 |
| 37 | Sonoma County | 10.83 |
| 38 | Santa Clara County | 10.81 |
| 39 | Contra Costa County | 10.26 |
| 40 | Siskiyou County | 10.09 |
| 41 | Butte County | 9.66 |
| 42 | Calaveras County | 9.20 |
| 43 | San Mateo County | 9.18 |
| 44 | Mariposa County | 9.13 |
| 45 | Humboldt County | 9.01 |
| 46 | Shasta County | 8.94 |
| 47 | Amador County | 8.69 |
| 48 | San Luis Obispo County | 8.07 |
| 49 | Inyo County | 7.92 |
| 50 | Tuolumne County | 7.91 |
| 51 | Marin County | 6.58 |
| 52 | Alpine County | 6.30 |
| 53 | Trinity County | 6.12 |
| 54 | Sierra County | 5.64 |
| 55 | Plumas County | 5.45 |
| 56 | El Dorado County | 5.32 |
| 57 | Placer County | 5.17 |
| 58 | Nevada County | 4.87 |