| Aleutian and Bering Sea Islands |
| Appalachian |
| Arctic |
| California |
| Desert |
| Eastern Tallgrass Prairie and Big Rivers |
| Great Basin |
| Great Northern |
| Great Plains |
| Gulf Coast Prairie |
| Gulf Coastal Plains and Ozarks |
| North Atlantic |
| North Pacific |
| Northwestern Interior Forest |
| Pacific Islands |
| Peninsular Florida |
| Plains and Prairie Potholes |
| South Atlantic |
| Southern Rockies |
| Unclassified |
| Upper Midwest and Great Lakes |
| Western Alaska |