Law and legislation National parks and reserves 41 Boundaries 30 Historic sites 25 Wild and scenic rivers 20 Land titles 14 Registration and transfer 14 更多 ... Water resources development 12 Water reuse 12 Wildlife conservation 12 Appropriations and expenditures 11 Endangered species 11 Public lands 11 Conservation 10 Finance 10 Forest reserves 10 War memorials 10 National monuments 9 Wilderness areas 9 Energy development 8 Coastal zone management 7 Cultural property 7 Land use 7 Natural areas 7 Protection 7 Research 7 Trails 7 Wildlife refuges 7 Hydroelectric power plants 6 Indians of North America 6 少 ...