Topic
- Harbors 22
- Waterfalls 21
- Building 18
- Covered bridges 18
- Historic bridges 17
- Mooring of ships 17
- Railroad bridges 17
- Railroads 17
- Crowds 16
- Bridges--Design and construction 15
- Columbia River Highway (Or.) 15
- Forests and forestry 14
- Railroad tracks 14
- Cliffs 13
- Columbia River 13
- Construction projects 13
- Railroad trains 13
- Steamboats 13
- Multnomah Falls (Or.) 12
- Steel Bridge (Portland, Or.) 12
