Subject
- Boundaries18
- Administrative and political divisions10
- Counties7
- Society4
- States4
- Environment3
- Protected areas3
- Wilderness areas3
- Biology and Ecology2
- Elementary schools2
- Inland Waters2
- School districts2
- Wilderness area monitoring2
- Battlefields1
- Conservation easements1
- Farming1
- Forest reserves1
- High schools1
- Historic parks1
- Historic sites1