Racially concentrated areas of affluence, by the researchers' definition, are census tracts where 90 percent or more of the population is white and the median income is at least four times the federal poverty level, adjusted for the cost of living in each city. Racially concentrated areas of poverty, by contrast, are census tracts where more than 50 percent of the population is non-white, and more than 40 percent live in poverty.

Detroit has 55 racially concentrated areas of affluence and 147 racially concentrated areas of poverty, according to the research, done by Ed Goetz, Tony Damiano, and Jason Hicks. Detroit's racially concentrated areas of affluence are just 1.1 percent black. Its racially concentrated areas of poverty, by contrast, are 76 percent black.

Cities such as St. Louis, Boston, Baltimore, and Minneapolis have more racially concentrated areas of affluence (RCAAs) than they do racially concentrated areas of poverty (RCAPs). Boston has the most RCAAs of the cities they examined, with 77. St. Louis has 44 RCAAs, and 36 RCAPs. Other cities with a large number of racially concentrated areas of affluence include Philadelphia, with 70, Chicago, with 58, and Minneapolis, with 56.

In Boston, 43.5 percent of the white population lives in census tracts that are 90 percent or more white and have a median income of four times the poverty level. In St. Louis, 54.4 percent of the white population lives in such tracts.

Still, it's the poor areas, rather than the areas where whites have self-segregated, that get the most attention from policymakers, who have sought to ameliorate concentrated poverty in segregated areas by moving families from black, urban areas to white suburbs. Beginning in 1989, the federal government started dismantling housing projects, spending billions to retool the type of housing available to low-income people in urban cores.

Programs may still integrate schools between white and black areas, as I’ve written about before, and they may move black families to white neighborhoods, as I’ve also detailed. But government programs don’t—and probably shouldn’t—move white families from wealthy areas to somewhere else (although they do provide incentives for home buyers or builders to locate in certain lower-income neighborhoods, thus beginning a process of gentrification).

Public policy has “focused on the concentration of poverty and residential segregation. This has problematized non-white and high-poverty neighborhoods,” said Goetz, the director of the Center for Urban and Regional Affairs at the University of Minnesota, when presenting his findings at the Lincoln Institute of Land Policy. “It’s shielded the other end of the spectrum from scrutiny—to the point where we think segregation of whites is normal.”