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- Architecture, American 55
- Architecture--United States 55
- Northwest, Pacific 6
- River engineering 6
- United States--Appropriations and expenditures 6
- Roads--Design and construction 5
- Scenic byways 5
- Photography 4
- West (U.S.) 4
- Railroad engineering 3
- Bodies of water 2
- Bridges 2
- Canals--Design and construction--Costs 2
- United States. Congress--Records and correspondence 2
- Waterfalls 2
- Dams--Design and construction 1
- Formations (Geology) 1
- Locks (Hydraulic engineering) 1
- Tunnels 1