2025 Theses Doctoral

Essays in Urban and Spatial Economics

Easton, Matthew

The essays in this dissertation concern the distribution of people and economic activity across space at the national, regional, and urban levels.

The first chapter studies the consistent power law observed in city-size distributions across countries, often referred to as Zipf’s law. To study this phenomenon, we analyze a general spatial equilibrium framework with heterogeneous locations, where trade and the locational productivities and amenities are subject to random variation in geographic and climatic characteristics. We prove how population is distributed spatially due to such random variation across space, demonstrating how population is lognormally distributed within countries and that the largest locations, i.e. cities, within countries appear to follow a power law.

The second chapter studies changes in the distribution of people regionally in the United States between 1940 and 2000. The “Sun Belt" is a region of the southern United States notable for significant population growth in recent decades, and an intuitive explanation is that the quality of life in the region rose due to increased valuation of weather-related amenities. Existing amenity value estimates for the Sun Belt from canonical spatial equilibrium models, however, are low and are estimated to have fallen in recent decades. I investigate two hypotheses using the canonical Rosen-Roback equilibrium framework: that amenity valuations have fallen in the Sun Belt during the 20th century, and whether geography and climate were an important channel affecting quality of life and population growth. I find that between 1940 and 2000, amenity values in the Sun Belt rose, in contrast to previous claims in the literature. However, using instrumental variables analy- sis, I find that weather’s effect on quality of life is not a significant driver of Sun Belt migration in canonical spatial equilibrium models.

The third and final chapter studies patterns in racial segregation in American cities between 1970 and 2000. We build a general equilibrium discrete choice model with spatial spillovers on racial preferences, with the model itself nesting canonical theories from the economics literature about the cross-section and dynamics of segregation. We simulate the model and test its predictions on U.S. Census data, finding that racial segregation is an inherently spatial phenomenon. In particular and in contrast to much of the existing literature, we find that people of the same race cluster in nearby neighborhoods, that clusters are common features of U.S. cities across time, and that racial change occurs at the boundaries of clusters.