Subject
National parks and reserves
11
Big Bend National Park (Tex.)
6
Fort Davis National Historic Site (Tex.)
5
Historic sites
5
San Antonio Missions National Historical Park (San Antonio, Tex.)
5
Chamizal National Memorial (El Paso, Tex.)
4
Environmental impact analysis
4
Wild and scenic rivers Recreational use
4
Big Bend National Park (Tex.) Environmental conditions
3
Big Thicket National Preserve (Tex.)
3
Conservation of natural resources
3
Geology
3
National parks and reserves Management
3
Rio Grande (Colo.-Mexico and Tex.) Environmental conditions
3
Wild and scenic rivers
3
Wilderness areas
3
Amistad National Recreation Area (Tex.)
2
Amistad National Recreation Area (Tex.) Management
2
El Chamizal (Mexico and Tex.)
2
Environmental impact statements
2
Indians of North America Antiquities
2
Land use
2
National parks and reserves Planning
2
Recreation areas Planning
2
Riparian animals
2
Rivers Recreational use
2
Stream animals
2
Stream conservation
2
Trails
2
Water resources development
2
Amistad National Recreation Area (Tex.) Antiquities
1
Battlefields
1
Battlefields Planning
1
Big Bend National Park (Tex.) Management
1
Chamizal National Memorial (El Paso, Tex.) Management
1
Chamizal National Memorial (Tex.)
1
Chihuahua Trail Environmental conditions
1
Droughts Environmental aspects
1
El Camino Real de Tierra Adentro National Historic Trail (N.M. and Tex.)
1
El Camino Real de Tierra Adentro National Historic Trail (N.M. and Tex.) Environmental conditions
1
Excavations (Archaeology)
1
Fish communities
1
Fish populations
1
Freshwater fishes
1
Freshwater fishes Effect of water quality on
1
Gas well drilling Planning
1
Guadalupe Mountains National Park (Tex.) Management
1
Historic buildings
1
Historic sites Conservation and restoration
1
Historic sites Interpretive programs
1
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