Columbia subject headings:
Harvard subject headings:
Coal--Transportation--United States--Congresses.
Grain--Transportation--United States--Congresses.
Inland water transportation--United States--Congresses.
Inland water transportation--United States--Passenger traffic--Congresses.
Princeton subject headings:
Coal--United States--Transportation--Congresses.
Grain--United States--Transportation--Congresses.
Inland water transportation--United States--Congresses.
Inland water transportation--United States--Passenger traffic--Congresses.