The Diversity Index is a scale of 0 to 100 that represents the likelyhood that two persons, chosen at random from the same area, belong to different race or ethnic groups. If an area's entire population belongs to one race AND one ethnic group, then the area has zero diversity. An area's diversity index increases to 100 when the population is evenly divided into two or more race/ethnic groups.
| County | Diversity Index | |
|---|---|---|
| 1. | San Joaquin County | 87.4 |
| 2. | Los Angeles County | 86.8 |
| 3. | Kings County | 86.3 |
| 4. | Fresno County | 85.5 |
| 5. | San Bernardino County | 85.2 |
| 6. | Monterey County | 84.9 |
| 7. | Kern County | 84.0 |
| 8. | Merced County | 83.7 |
| 9. | Riverside County | 83.3 |
| 10. | Solano County | 83.3 |
| 11. | Alameda County | 82.6 |
| 12. | Tulare County | 82.0 |
| 13. | Madera County | 81.5 |
| 14. | San Benito County | 81.0 |
| 15. | Stanislaus County | 81.0 |
| 16. | Sutter County | 80.9 |
| 17. | Colusa County | 80.7 |
| 18. | Orange County | 80.2 |
| 19. | Santa Clara County | 80.1 |
| 20. | Contra Costa County | 79.9 |
