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Topic
- United States--Appropriations and expenditures 38
- West (U.S.) 37
- River engineering 35
- Canals--Design and construction--Costs 30
- Dams--Design and construction 30
- Transportation 30
- Bodies of water 27
- Rivers 26
- Northwest, Pacific 25
- Water resources development 25
- River surveys 22
- United States. Congress--Records and correspondence 9
- Locks (Hydraulic engineering) 5
- Railroad engineering 3
- Bridges--Design and construction 2
- Military maps 2
- Military topography 2
- Bird's-eye view prints 1
- Bridges 1
- Cascade Range 1