I. Introduction  3

II. Motivating Facts: Convergence, Stagnation, and Falling Back  6

III. A Model of Convergence with Moving Steady States  8

IV. Empirical Framework and Results  12

V. Convergence, Fragility, and Distribution Dynamics  24

VI. Conclusion  25

References  26

Appendix A. Dynamic Convergence with Moving Steady States  28

Appendix B: Supplementary Empirical Results and Robustness Analysis  33