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Topic
- Lectures and lecturing 19
- Architecture, American 14
- Architecture--United States 13
- Rivers--Oregon 12
- Water--Pollution 10
- Sewage disposal plants 8
- Crowds 4
- Marquees 4
- Parade floats 4
- Portland Rose Festival (Portland, Or.) 4
- Buildings 3
- Izaak Walton League of America 3
- Ships 3
- Bands (Music) 2
- Birds--Conservation 2
- Bodies of water 2
- Conservation of natural resources 2
- Crickets 2
- Dams 2
- Ducks 2
