The Boundaries of Spatial Inequality: Three Essays on the Measurement and Analysis of Residential Segregation

Ph.D. Thesis, Yale University (May 2015)

My dissertation introduces new methodological approaches for studying the spatial context of residential segregation. It bridges qualitative insight on the local experience of unequal social environments and how we measure segregation for city populations. In the first essay, I introduce the Divergence Index, a conceptually intuitive and methodologically rigorous measure of inequality and segregation. It can be interpreted as a measure of surprise: how surprising is the composition of an individual's local environment given the overall population of the city? The second essay presents a new method for capturing the spatial relationships and structured patterns that we commonly recognize as residential segregation. I measure the distance between residential locations along city roads. Road distance is a more realistic measure of proximity than the straight line ("as the crow flies") distance used in previous approaches. It captures the connectivity of roads and the excess distance imposed by spatial boundaries, such as rivers and highways. Together, the first two essays address fundamental measurement issues that have limited previous efforts to describe the spatial dynamics and local context of residential segregation. In the third essay, I apply my new method and measure in an empirical analysis of racial and ethnic residential segregation in U.S. cities. I find that cities previously thought to have similar levels of segregation, nonetheless have different spatial patterns of segregation. Results reveal the salience of city boundaries in structuring segregation patterns in Detroit, and how the presence of physical boundaries affects the composition of local environments in Manhattan. Further, the experience of segregation is highly unequal within some cities, such as St. Louis. Some residents live in completely segregated environments, while others live in areas that are a microcosm of the city's diverse population. In these cities of extremes, local segregation is both better and worse than indicated by the city's overall segregation. My emphasis on spatial boundaries and local context reframes our understanding of segregated environments, and offers deeper insight into even the most studied U.S. cities, including Milwaukee and Philadelphia.