Columbia subject headings:
Emigration and immigration.
Natural resources--United States.
Natural resources.
Population forecasting--United States.
Population forecasting.
Population.
United States--Emigration and immigration.
United States--Population.
Harvard subject headings:
Emigration and immigration.
Natural resources--United States
Natural resources.
Population forecasting--United States.
Population forecasting.
Population.
United States--Emigration and immigration.
United States--Population.
Princeton subject headings:
Emigration and immigration.
Natural resources--United States.
Natural resources.
Population forecasting--United States.
Population forecasting.
Population.
United States--Emigration and immigration.
United States--Population.