From a Vox article titled “White America is quietly self-segregating”:
Research led by Lichter, the Cornell sociologist, shows that in the past 25 years, the segregation between white people and minorities hasn’t changed much within cities; racial groups are still very separate, though slightly less so. What has changed, though, is how segregated one town is from another.
White families are increasingly self-segregating themselves in new ways — and it’s largely in the form of their moving decisions. Lichter’s research shows white households are now moving to what sociologists call the “exurbs” — gated communities, unincorporated housing developments, and the countryside. This is why the only communities in the US that have seen significant white growth are places that were already predominantly white.
“You’ve got one group of white Americans who are comfortable with diversity and integrating with minorities, including blacks and Hispanics and Asians,” he said, “and another America that is hunkering down in overwhelmingly white areas in overwhelmingly white places — and you see them moving further out.”