To determine the most segregated cities, 24/7 Wall St. calculated the percentage of 29 metro area residents living in homogeneous zip codes, defined as areas with at least 80% of a single racial or ethnic group. Without these pockets of single racial groups, segregation would not be possible. Using five-year estimates from the U.S. Census Bureau’s 2013 American Community Survey (ACS), we identified each homogeneous zip code with more than 100 residents in the 50 metro areas with populations greater than 1 million. Metro areas where residents in homogeneous zip were of just a single race were excluded. For example, the Washington D.C. metro area was not considered because all of its isolated zip codes were more than 80% white. This is not to suggest that Washington D.C. is free from segregation, but rather that we could not determine the level of segregation from the zip code data. Richard Rothstein, research associate at the EPI, believes every U.S. metro area has an unacceptable degree of segregation.
After identifying the homogeneous zip codes in each metro area, we determined the segregated population — that is, those living in the zip codes’ racial or ethnic majorities. For example, if a metro area had five white-isolated zip codes, we added the white populations in each of those zip codes. Then, we identified the share of a metro area’s racial population living in homogeneous zip codes. Our main rank is the sum of all segregated populations as a percentage of a metro area’s total population. To gain a broader picture of segregation in the area, we combined an area’s Asian and white populations into one group and the black and Hispanic populations into another group and repeated our analysis.
We also measured segregation with other, widely used methods — dissimilarity and exposure indices — which correlate well with our own segregation score. The dissimilarity index measures how evenly a population is distributed throughout zip codes in a metro area. The exposure index describes how likely members of two racial groups are to come in contact with each other. Together, these two indices offer a more nuanced view of segregation in some areas.
Additionally, we reviewed median household income, poverty rates, educational attainment rates, and homeownership rates in each metro area from the ACS. All data are five-year estimates and are broken out by race. We also included 2013 unemployment rates by race from the Bureau of Labor Statistics (BLS).