The simplest way to explain their conclusion may be to point out that upward mobility tends to be rare for both blacks and whites, as well as for Latinos, in low-mobility areas. In Charlotte, Atlanta and Indianapolis, low-income white children have also tended to grow up to be low-income adults.
To help demonstrate this pattern, the four researchers – Raj Chetty and Nathaniel Hendren of Harvard and Patrick Kline and Emmanuel Saez of the University of California, Berkeley – have produced another map, showing mobility only for ZIP codes that are at least 80 percent white. (ZIP codes that are less than 80 percent simply appear as blank on the map.)
But the message is clear: the mobility patterns look overwhelmingly similar in this map and in the map above showing all metropolitan areas.
It’s worth pointing out that race may still play a role in creating these patterns. “Racial shares in an area do matter,” Mr. Chetty says. “But it’s not race at the individual level. It’s race at the level of the ‘commuting zone,’” he added, using the researchers’ term for a region. Whatever the differences are between high-mobility and low-mobility regions, they seem to apply to residents of every race.
Writing about the new study for The Atlantic, Matthew O’Brien laid out a specific case for how race might have created economic segregation in sprawl-filled regions:
Atlanta, of course, is the prototypical case here: going back to the 1970s, it’s under-invested in public transit,
Sprawl might be one factor, but how long does it take to come up with a list of old fashioned cities like Baltimore, Cleveland, St. Louis, Newark, Hartford, and Milwaukee with intense black poverty? (Of course, if, say, whites in Hartford flee to the suburbs, leaving a black core, then that's "job sprawl." That's so unfalsifiable that if Sir Karl Popper were alive today, he'd be spinning in his grave.)