The return of convergence in the US states

We analyse convergence of per capita income across the US states for the period 1929--2011. We find that absolute convergence was in evidence early, but it broke down around 1978. It appears to have returned in 1990, although more weakly than before. We use two standard metrics to evaluate convergence: (1) <italic>σ</italic>-convergence, a reduction in the SD of state per capita income and (2) <italic>β</italic>-convergence, the fact that poor states grow faster than rich states.