Atlanta's a good example of a city that's quite sprawling, where there's a sharp division between where blacks and whites live, between where low-income and high-income families live.

We don’t really care about test scores. We care about adult outcomes.

Every extra year you spend in a better environment makes you more likely to go to college, less likely to have a teenage pregnancy, makes you earn more as an adult, makes you more likely to have a stable family situation, be married, for instance, when you're an adult.

Cities that tend of have better schools for middle-income families, they tend to have much better prospects for kids moving up in the income distribution.

The data show we can do something about upward mobility. Every extra year of childhood spent in a better neighborhood seems to matter.