This paper examines the growth and dispersion of personal income in U.S. states and regions since 1880, and relates the patterns for individual states to the behavior of regions. It analyzes the interplay between net migration and economic growth, and studies the evolution of gross state product since 1963, relating the behavior of aggregate product to productivity in eight major sectors. The overall evidence supports convergence: poor states tend to grow faster in terms of per capita income and product and within sectors as well as for state aggregates. The rate of convergence is not rapid: the gap between the typical poor and rich state diminishes at roughly 2% per year. The same framework is applied to patterns of convergence across 73 regions of seven European countries since 1950. The process of convergence within European countries is similar to that for the United States. In particular, the rate of convergence is again about 2% per year. The paper concludes by using the findings to forecast the convergence process for the eastern regions of unified Germany. The results are not very encouraging: if the histories of the U.S. states and European regions are useful guides, then the convergence process will occur, but only at a slow pace. The paper discusses the neoclassical growth model and its implications for convergence. It shows that the transitional growth process in the neoclassical model can be approximated as a log-linear approximation from the transition path of the neoclassical growth model for closed economies. The convergence coefficient β depends on the productivity of capital and the willingness to save. The paper also discusses the role of migration in the convergence process, showing that net migration from poor to rich states speeds up the convergence of per capita income. The paper finds that the estimated convergence coefficient β is about 2% per year. The results suggest that β convergence occurs at a rate somewhat above 2% per year. The paper also discusses the role of regional differences and the impact of technological diffusion on convergence. It finds that the long-term decline in the cross-sectional standard deviation of per capita income is due to the convergence of regions toward similar steady-state behavior of per capita income. The paper also discusses the role of migration in the convergence process, showing that net migration from poor to rich states speeds up the convergence of per capita income. The paper concludes that the convergence process is slow and that the results suggest that β convergence occurs at a rate somewhat above 2% per year.This paper examines the growth and dispersion of personal income in U.S. states and regions since 1880, and relates the patterns for individual states to the behavior of regions. It analyzes the interplay between net migration and economic growth, and studies the evolution of gross state product since 1963, relating the behavior of aggregate product to productivity in eight major sectors. The overall evidence supports convergence: poor states tend to grow faster in terms of per capita income and product and within sectors as well as for state aggregates. The rate of convergence is not rapid: the gap between the typical poor and rich state diminishes at roughly 2% per year. The same framework is applied to patterns of convergence across 73 regions of seven European countries since 1950. The process of convergence within European countries is similar to that for the United States. In particular, the rate of convergence is again about 2% per year. The paper concludes by using the findings to forecast the convergence process for the eastern regions of unified Germany. The results are not very encouraging: if the histories of the U.S. states and European regions are useful guides, then the convergence process will occur, but only at a slow pace. The paper discusses the neoclassical growth model and its implications for convergence. It shows that the transitional growth process in the neoclassical model can be approximated as a log-linear approximation from the transition path of the neoclassical growth model for closed economies. The convergence coefficient β depends on the productivity of capital and the willingness to save. The paper also discusses the role of migration in the convergence process, showing that net migration from poor to rich states speeds up the convergence of per capita income. The paper finds that the estimated convergence coefficient β is about 2% per year. The results suggest that β convergence occurs at a rate somewhat above 2% per year. The paper also discusses the role of regional differences and the impact of technological diffusion on convergence. It finds that the long-term decline in the cross-sectional standard deviation of per capita income is due to the convergence of regions toward similar steady-state behavior of per capita income. The paper also discusses the role of migration in the convergence process, showing that net migration from poor to rich states speeds up the convergence of per capita income. The paper concludes that the convergence process is slow and that the results suggest that β convergence occurs at a rate somewhat above 2% per year.