Historical Census - years (1790 to 1960)
Historical Census data is available from the University of Virginia. This site presents data for the people and the economy of the U.S. for each state and county from 1790 to 1960.
Population Estimates - years (2010 to Current)
These data are produced by the U.S. Census Bureau for the U.S. and States, from 2010 to current.
Population Forecasts - years
Population projections are produced by the U.S. Census Bureau for the U.S. and States from 1999 to 2100.