Columbia subject headings:
Monopolies--United States.
Railroads--Freight--Rates--United States.
Railroads--Freight--United States.
Harvard subject headings:
Monopolies--United States.
Railroads--Freight--Rates--United States
Railroads--Freight--United States
Princeton subject headings:
Monopolies--United States.
Railroads--Freight--Rates--United States.
Railroads--Freight--United States.