The changing shape of spatial inequality in the United States

Spatial income disparities have increased in the United States since 1980. Growth in this form of inequality is linked to major social, economic and political challenges. Yet, contemporary patterns, and how they relate to those of the past, remain insufficiently well understood. Building on population survey microdata spanning 1940-2019, this paper uses group-based trajectory modelling techniques to identify distinct sets of local labor markets based on the evolution of their income levels. We find that the increase in spatial inequality since 1980 is almost entirely driven by a small number of populous, economically-important, and resiliently high-performing `superstar' city-regions. Meanwhile, since 1940, much of the rest of the urban system has continued to converge toward the mean. We examine the demographic, economic and social characteristics of these different trajectories, identifying catch-up regions, declining regions, long-term winners, and possible future superstars. There is considerable turbulence within the convergence process, consisting of regions that are moving both upward and downward in the system. We conclude by exploring implications for the American urban-regional system in the mid-21st century, considering the challenges in overcoming the growing split between superstar locations and the rest of the country.