Columbia subject headings:
Labor supply--United States.
United States--Census, 1940.
World War, 1939-1945--Manpower--United States.
Harvard subject headings:
Labor supply--United States.
United States--Census, 1940.
World War, 1939-1945--Manpower--United States.
Princeton subject headings:
Occupations--United States.
United States--Census, 1940.