Over the past forty years, income inequality in the United States has grown rapidly. The top 1% of earners earned 21% of all income in the United States in 2012, two and a half times the 8.4% share they earned in 1970. A family at the 90th percentile of the income distribution now earns almost 10 times as much as a family at the 10th percentile of the income distribution; in 1970 the same families’ incomes would have differed by a factor of 6.
One consequence of this rising income inequality has been a similarly sharp increase in residential income segregation. As the chart below illustrates, in 1970, two-thirds of American families in large metropolitan areas lived in middle-income neighborhoods—neighborhoods with median incomes between 80% and 125% of the median income in their metropolitan area. By 2007, that number had declined by a third: only 43% of families lived in such neighborhoods. Instead, a growing number of families now live in neighborhoods that are either very poor or very affluent. Middle-class neighborhoods, like the middle class, are rapidly disappearing.
This website provides a look at the patterns and trends in residential income segregation over the past forty years in the two dozen most populated metropolitan areas of the United States. We focus here on the segregation of families because segregation may be particularly consequential for children. Children are less mobile than adults, so where they live may play a much larger role in shaping their experiences, friendships, social interactions, and educational opportunities than it may for adults.
Use the map or the dropdown menu below to navigate to different metropolitan areas and explore how segregation patterns have changed over time in any of these places.
Data Sources and Calculations
The data here are from the 1970, 1980, 1990, and 2000 U.S. Census and the 2005-09 American Community Survey (we refer to the 2005-09 period as “2007” for simplicity here). The Census and American Community Survey provide information on the distribution of family income in each census tract (a census tract is a neighborhood with a population of roughly 4,000 people).
For each year, we calculated the median income of families in each of the largest metropolitan areas, and the median income of families in each census tract in those metropolitan areas. We then computed, for each of these census tracts, the ratio (r) of the tract’s median family income to that of its metropolitan area. Based on this ratio, we classified each tract as affluent (r≥1.50); high-income (1.25≤r<1.50); high middle-income (1.00≤r<1.25); low middle-income (0.80≤r<1.00); low-income (0.67≤r<0.80); or poor (r<0.67). An affluent neighborhood, therefore, is one where more than half of the families have incomes at least one-and-a-half times greater than the median income in their metropolitan area. Likewise, a poor neighborhood is one where more than half of the families have incomes less than two-thirds of the median income in their metropolitan area. These definitions make it possible to compare neighborhood income levels over time, even as the income distribution in metropolitan areas changes. They also allow us to compare patterns across metropolitan areas, despite differences in their local income distribution and cost-of-living.
In 1970 and 1980, not all areas of the United States were divided into census tracts. On the maps on the following pages, these “non-tracted areas” are shown in white, indicating we have no income data for those places. Generally, only sparsely-populated semi-rural regions on the periphery of metropolitan areas were non-tracted in 1970 and 1980; the absence of data for these places has little effect on the calculation of segregation trends.
Further Reading and Resources
For more information on income segregation patterns, trends, and causes, and for more detail on the data and methods used to produce the figures on this site, please see:
Sean F. Reardon and Kendra Bischoff. Income Inequality and Income Segregation. American Journal of Sociology, Vol. 116, No. 4 (January 2011), pp. 1092-1153.
Sean F. Reardon and Kendra Bischoff. Growth in the Residential Segregation of Families by Income, 1970-2009. US2010 Project. (November 2011)
Kendra Bischoff and Sean F. Reardon. Residential Segregation by Income, 1970-2009. US2010 Project. (October 2013)
Download tract-level data for the metropolitan areas shown here.
Download metropolitan area data for the metropolitan areas shown here.
Download additional segregation measures for all U.S. metropolitan areas from the US2010 Project.