| 65 Southeastern Plains |
| 65a Blackland Prairie |
| 66 Blue Ridge Mountains |
| 67 Ridge and Valley |
| 68 Cumberland Plateau |
| 69 Cumberland Mountains |
| 70 Allegheny Plateau |
| 71 Interior Plateau |
| 71 Bluegrass Region |
| 71 Nashville Basin |
| 71e Pennyroyal Karst Plain |
| 71f Western Highland Rim |
| 71g Eastern Highland Rim |
| 72 Interior River Valleys and Hills |
| 72h Shawnee / Caseyville Hills |
| 73 Mississippi Alluvial Plain |
| 74 Mississippi Valley Loess Plains |
