Columbia subject headings:
Agriculture and state--Congresses.
Free trade--Congresses.
Produce trade--Congresses.
Tariff on farm produce--Congresses.
Harvard subject headings:
Agriculture and state--Congresses.
Free trade--Congresses
Produce trade--Congresses
Tariff on farm produce--Congresses.
Princeton subject headings:
Agriculture and state--Congresses.
Free trade--Congresses.
Produce trade--Congresses.
Tariff on farm produce--Congresses.