Columbia subject headings:
Natural resources--United States.
Reclamation of land--United States.
United States--Economic conditions--1918-1945.
United States--Economic policy.
Harvard subject headings:
Maps
Natural resources
Reclamation of land--United States
United States--Economic conditions--1918-1945
United States--Economic policy--1933-1945
Princeton subject headings:
Natural resources.
Reclamation of land--United States.
United States--Economic conditions--1918-1945.
United States--Economic policy--1933-1945.