Five census facts predict almost half the variation in neighborhood upward mobility. This story is about the other half — the counties whose poor children climb five or six percentiles higher than their demographics predict, and the sunbelt boomtowns that fall just as far short.
Every model is a foil. Regress each tract's upward mobility — the adult income rank of children raised there in low-income families — on five ordinary census facts (poverty, college share, single-parent share, log income, Black share) and you explain 44 percent of the variance. That is the boring half of the story, mostly restating earlier chapters.
The interesting half is the disagreement. Where do children systematically out-climb what those five facts predict? A residual is not noise when it has a geography — it is a list of places that know something the model doesn't.
Each dot is a tract: the model's prediction against what actually happened to the children. The diagonal is perfect prediction; the vertical scatter is everything five census facts cannot see — schools, networks, churches, transit, safety, the local labor market, and luck.
Average the residuals by county and the disagreement organizes itself. The green belt of overperformance runs through the New York orbit — Staten Island (+6.3), Nassau, Bergen, Queens — and the immigrant-dense, union-dense, transit-dense Northeast generally, plus the rural Plains. The red belt of underperformance is the fast-growing Sunbelt and the scenic boomtowns: Denver (−5.4), Asheville's Buncombe County (−5.3), Knoxville, Durham, St. Johns FL. Places that look demographically alike launched their poor children very differently.
Compare the top and bottom tenth of counties. The overperformers are five times denser, more immigrant, less smoking-prone — and, crucially, they are old places: established urban regions whose 1980s neighborhoods still resemble themselves. The underperformers are disproportionately places that boomed after these children grew up. That timing is a warning and a finding at once: part of the residual is history — the model sees today's census; the children lived in yesterday's county. But the New York orbit's edge survives every cut we tried, echoing the Atlas literature's own conclusion that dense immigrant metros punch far above their poverty rates.
A residual map is the most honest to-do list a book can have. Each green county is a candidate mechanism — networks, transit, parishes, public sectors, immigrant scaffolding — and each red one a candidate failure worth a chapter visit. The model's job was never to be right; it was to subtract the obvious so that the non-obvious has somewhere to stand.