Columbia subject headings:
Freight and freightage--United States.
Railroads--Freight--Rates--United States.
Railroads--Freight--United States--Forecasting.
Railroads--United States--Traffic.
Harvard subject headings:
Freight and freightage--United States
Railroads--Freight--Rates--United States
Railroads--Freight--United States--Forecasting.
Railroads--United States--Traffic.
Princeton subject headings:
Freight and freightage--United States.
Railroads--Freight--Rates--United States.
Railroads--Freight--United States--Forecasting.
Railroads--United States--Traffic.