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. | Starr County | 14.7 |
| 2. | Zapata County | 21.6 |
| 3. | Clay County | 24.7 |
| 4. | Maverick County | 25.2 |
| 5. | Archer County | 28.3 |
| 6. | Armstrong County | 28.4 |
| 7. | Hardin County | 29.2 |
| 8. | Webb County | 30.0 |
| 9. | Sabine County | 30.3 |
| 10. | Llano County | 31.8 |
| 11. | Callahan County | 31.8 |
| 12. | Carson County | 32.2 |
| 13. | Brooks County | 32.5 |
| 14. | Shackelford County | 33.2 |
| 15. | Zavala County | 33.2 |
| 16. | Montague County | 33.8 |
| 17. | Hidalgo County | 34.1 |
| 18. | Jim Hogg County | 34.4 |
| 19. | Rains County | 34.4 |
| 20. | Roberts County | 34.7 |
