Dwindling U.S. internal migration: Evidence of spatial equilibrium or structural shifts in local labor markets?

This paper examines whether the significant downward shift in U.S. gross migration rates after 2000 is indicative of the economy nearing a stationary spatial equilibrium characterized by relatively small population growth differentials. Nearing spatial equilibrium would imply that site-specific factors such as amenities and location within the urban hierarchy substantially subside in their influence on net-migration and relative population growth because their values have been capitalized into prices, causing interregional utility levels to become approximately equal. Yet, in an examination of U.S. counties, we find empirical evidence of only slight ebbing of natural amenity-based migration after 2000 and little slowing of population redistribution from peripheral towards core urban areas. Instead, the primary finding is a downward shift in the responsiveness of relative population growth to spatially asymmetric demand shocks post-2000, and associated increased responsiveness of local area labor supply, more consistent with European regional labor markets. Additional sensitivity analysis, including instrumental variable estimation, confirms the result. Quantile regression analysis suggests that our findings are not due to a difference in regional labor market tightness between the 1990s and post-2000.