Topic
- Iron and steel bridges 9
- Klickitat River (Wash.) 9
- Landscape photography 9
- United States--Armed Forces--Organization--Charts, diagrams, etc 9
- Columbia River Watershed 8
- Harbors 8
- West (U.S.) 8
- Celilo Falls (Wash.) 7
- Trees 7
- Indians of North America 6
- John Day River (Or.) 6
- Nature 6
- Rocks 6
- Steamboats 6
- Boats and boating 5
- Inland navigation 5
- Riparian areas 5
- Abandoned buildings 4
- Bridges--Design and construction 4
- Irrigation canals and flumes 4