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α: calibrated so average coauthorship-adjusted count equals average raw count
We study the evolution of the cross‐sectional distributions of county‐level per capita income in the United States from 1970 to 2017. We confirm previous findings of convergence in pre‐transfer income during the 1970s and 1980s but present new evidence of rising inequality since the early 1990s, which is characterized by bipolarization. Cross‐county differences in education and industry composition explain much of this recent trend, which almost disappears in post‐transfer incomes. Among the various government transfer programs, medical benefits play the greatest role in making the distribution less unequal.