In this paper we outline (i) why sigma-convergence may not accompany beta-convergence, (ii) discuss evidence of beta-convergence in the U.S., and (iii) use U.S. county-level data containing over 3,000 cross-sectional observations to demonstrate that sigma-convergence has not occurred at the...

We use U.S. county-level data containing 1,921 cross-sectional observations and up to 29 conditioning variables to estimate heterogeneity in convergence rates across 22 individual U.S. states. Applying GMM estimation, we find significant heterogeneity in the state-level convergence rates. For...