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- West (U.S.) 141
- River engineering 106
- Bodies of water 104
- Northwest, Pacific 103
- Railroad engineering 48
- Canals--Design and construction--Costs 35
- United States--Appropriations and expenditures 35
- Transportation 30
- Dams--Design and construction 29
- Rivers 27
- Water resources development 27
- Locks (Hydraulic engineering) 6
- Railroad construction & maintenance 1
- River surveys 1
