Law and legislation 761 Land titles 171 Registration and transfer 171 National parks and reserves 169 Historic sites 119 Boundaries 112 Water resources development 67 more ... Finance 49 Cultural property 42 Protection 42 Hydroelectric power plants 40 Trails 40 Research 37 Real property, Exchange of 34 Public lands 33 Wilderness areas 31 Water reuse 28 Wild and scenic rivers 28 Appropriations and expenditures 26 Watershed management 25 Forest reserves 24 Monuments 23 Memorials 22 Recreation areas 22 Groundwater 20 Licenses 19 Water-supply 17 Energy conservation 15 Visitors' centers 15 Water 15 less ...