Raise two children on the same block — one in a family at the 25th income percentile, one at the 75th. The richer child will land, on average, 13.6 percentiles higher as an adult. But that premium is not a constant of nature: it is twice as large in Cincinnati as in the Bronx.
Most maps of opportunity — including two earlier stories in this series — follow the children of the poor. This one follows both ends of the ladder at once. For every census tract, the Opportunity Atlas reports the average adult income rank of children raised there at the 25th parental-income percentile and at the 75th. The difference between the two is something rare: a neighborhood-level price on class itself.
Two findings follow, and the first corrects a popular intuition.
The intuition says wealth insulates children from place — that rich kids turn out fine everywhere, while poor kids' fates swing with the neighborhood. Across tracts, that is simply not what the data show: the two distributions below are almost equally wide (a spread of about 7 percentiles either way). Place sorts the destinies of rich children nearly as much as poor ones. What differs is the starting line — the whole rich-kid distribution sits 13.6 percentiles to the right.
Plot each tract's rich-kid outcome against its poor-kid outcome and the cloud climbs with a slope of 0.70 — meaningfully less than one. Read that slope carefully, because it is the most hopeful number in this series: in tracts that lift poor children, rich children gain less than point-for-point. The places that are good for the poor are not simply "good for everyone equally" — they are places where origins matter less, where the two lines converge.
Aggregate the premium to counties and a geography appears that is the inverse of nearly every other map in this series. The class premium is smallest in the dense immigrant metros — the Bronx (8.0), Brooklyn (8.6), San Francisco (8.9), Los Angeles (9.1) — places that are famously hard on the poor in absolute terms but where rich birth buys surprisingly little extra. It is largest across the post-industrial Midwest and Appalachian edge — Cincinnati's Hamilton County (17.3), Luzerne County in Pennsylvania's anthracite country (16.9) — where being born comfortable is worth nearly a fifth of the entire national income ladder.
A small premium is not automatically good news. The Bronx compresses the class gap partly by holding its rich children down (p51 on average — among the lowest rich-kid outcomes in the country), not only by lifting its poor. The most enviable counties are the ones that combine a high floor with a small premium — and they are disproportionately the immigrant gateways and a band of Plains counties, places where, in Chetty's phrase, it is easier to buy your kids a future by moving than by earning.
And a caution this series repeats deliberately: these are descriptive averages over children who grew up in each place decades ago. The premium mixes neighborhood effects with everything families bring to a neighborhood. What the mover designs in the causal literature establish is that a meaningful share — roughly half, for young children — travels with the place itself.