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.

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.

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

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.