Columbia subject headings:
United States--Economic conditions--1918-1945.
United States--Economic conditions.
United States--Emigration and immigration.
Working class--United States.
Harvard subject headings:
Labor--United States
United States--Economic conditions.
United States--Emigration and immigration.
Working class--United States
Princeton subject headings:
Labor--United States.
United States--Economic conditions.
United States--Emigration and immigration.