Urbanization is linked to economic growth, and agglomeration economies mean that people in larger cities are more productive. However, urban expansion is also associated with congestion, localized environmental damage, and potentially, social segregation. In this paper we examine how urban expansion and changing urban spatial structure affects the level and scale of socioeconomic segregation of cities in Mexico. We measure different dimensions of urban spatial structure, and segregation by income and education at different geographic scales in 100 Mexican cities from 1990 to 2010. We then examine correlations between the two sets of variables, and run multivariate regressions to assess how changes in urban spatial structure relate to changes in the level and scale of segregation. Findings reveal that as cities expand, inhabitants experience greater levels of socioeconomic segregation, especially at a larger geographic scale. However, an increasing centralization of cities is associated with less segregation. This process works differently for segregation by education and income. For the former, less educated households are become more segregated in expanding, centralizing cities. For the latter, it is high-income households who are becoming more isolated. This study reveals provocative generalizations about the association between urban expansion and increasing segregation in Mexico. It suggests that movements into and out of central cities, rather than urban fragmentation or sprawl, shape how household mobility reorganizes social space.

This research is made possible by the generous support of the Ford Foundation's Building Economic Security Over a Lifetime initiative. We especially acknowledge our Ford Foundation Program Officers-Kilolo Kijakazi, Amy Brown, Leah Mayor, and John Irons. Funding was also provided by the UCLA Institute for American Cultures, UCLA Asian American Studies Center, UCLA Luskin Center for History and Policy, and the Haynes Foundation. This research is also part of the UCLA Center for Neighborhood Knowledge's (CNK) Kerner Revisited project. We are grateful to CNK staff, Chhandara Pech and Alycia Cheng, for their research and technical assistance.

Economic segregation in urban areas is important to scholars and policymakers because it is thought to exacerbate inequality in social outcomes such as education, social capital formation, and employment. A growing body of comparative work examines factors associated with higher levels of urban segregation within different countries. Increasingly, this work examines differences between levels of segregation across the income distribution rather than just one measure of segregation per city. China has high levels of income inequality and has undergone a dynamic process of urbanization in recent decades as it transitions from a centrally planned system to one in which markets allocate goods. Using census data from the 20 largest cities in China, we measure the level of economic segregation and examine its determinants. Chinese cities are highly segregated. Segregation levels tend to be higher in larger and richer cities and more pronounced among renters. There is a stronger link between segregation based on housing type and expenditure than between migrant status and expenditures, which leads us to speculate that the pace, timing, and scale of housing development are the dominant drivers of economic segregation. ARTICLE HISTORY

Mexico City is known as one of the largest cities in the world and thought by many to be one of the most unequal. Not surprisingly, it has received more attention than other Mexican urban areas. However, the city’s internal social organization is often misunderstood. Mexico City stands out as a city where segregation is relatively low, and levels of inequality are actually lower than perceptions. Moreover, between 1990 and 2010, both segregation and inequality have declined. This chapter examines these changes. We report on changes in occupational structure and patterns of segregation by educational level. Educational level is different from income or occupation, but these three dimensions of socioeconomic conditions are closely linked. While the overall level of segregation between educational groups in the city has slightly decreased, residential patterns of educational groups have changed significantly. The number of neighborhoods with high concentrations of highly educated people increased significantly and expanded geographically. At the same time, the prevalence of neighborhoods with residents with low and middle educational attainment has diminished and neighborhoods that house people of all educational categories or high and middle categories are more numerous. This chapter illustrates the complexity of segregation patterns in such a large metropolitan area, as well as the challenges of determining why patterns have changed.

This paper provides a comparative assessment of income segregation within cities in 12 countries. We use spatial entropy indexes based on small-scale gridded income data and consistent definition of city boundaries to ensure international comparability of our segregation measures. Results show considerable variation in the levels of income segregation across cities, even within countries, reflecting the diversity of cities within urban systems. Larger, more affluent, productive, and more unequal cities tend to be more segregated. Urban form, demographic, and economic factors explain additional variation in segregation levels through the influence of high-income households, who tend to be the most segregated. The positive association between productivity and segregation is mitigated in polycentric cities.