Columbia subject headings:
Emigration and immigration--Economic aspects.
Great Britain--Economic conditions.
Migration, Internal.
United States--Economic conditions.
Urbanization.
Harvard subject headings:
Emigration and immigration--Economic aspects
Great Britain--Economic conditions.
Migration, Internal
United States--Economic conditions.
Urbanization
Princeton subject headings:
Emigration and immigration--Economic aspects.
Great Britain--Economic conditions.
Migration, Internal.
United States--Economic conditions.
Urbanization.