Sigma Convergence versus Beta Convergence: Evidence from U.S. County-Level Data


  • We are grateful to the anonymous referee for constructive comments and suggestions. In addition, we thank Jordan Rappaport for kindly sharing with us some of his data and computer codes and for providing helpful suggestions throughout the study. All errors are ours.


In this paper, we outline (i) why σ-convergence may not accompany β-convergence, (ii) discuss evidence of β-convergence in the United States, and (iii) use U.S. county-level data containing over 3,000 cross-sectional observations to demonstrate that σ-convergence cannot be detected at the county level across the United States, or within the large majority of the individual U.S. states considered separately. Indeed, in many cases statistically significant σ-divergence is found.