Interregional Differences in Per Capita Income, Population, and Total Income, 1840-1950

Richard Easterlin, Trends in the American Economy in the Nineteenth Century (Princeton University Press, 1960), https://www.nber.org/books-and-chapters/trends-american-economy-nineteenth-century/interregional-differences-capita-income-population-and-total-income-1840-1950.