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Topic
- Coal74
- Gasoline43
- World War, 1939-194538
- Lungs--Dust diseases37
- Women--Suffrage37
- Economic development32
- Outdoor recreation32
- Natural gas31
- Reclamation of land--United States31
- Coal mines and mining28
- Housing28
- Railroads28
- Veterans28
- Flood control27
- Disaster relief24
- Small business24
- Education23
- Air travel21
- Coal--Transportation21
- Historic preservation20
