1. Northeast	11. Southern Plains
2. Mid-Atlantic	12. Northern Rocky Mountains
3. Southeast	13. Southern Rocky Mountains
4. Atlantic Neotropical	14. Desert Southwest
5. Great Lakes	15. Great Basin
6. Prairie Peninsula	16. Pacific Northwest
7. Appalachians/Cumberland Plateau	17. Pacific Southwest
8. Ozark Complex	18. Tundra
9. Northern Plains	19. Taiga
10. Central Plains	20. Pacific Neotropical