Where in America should you live?

The central tenet of the American Dream is the prospect of social mobility across generations. In America today, there are places where such mobility is more possible than others.

Economist Raj Chetty and his collaborators (Hendren, Kline, and Saez) have studied this question for years. So have Melissa Kearney, Richard Reeves, Charles Murray, and others. There are five characteristics that consistently mark the kinds of communities where Americans experience upward mobility.

Areas with less residential segregation, by income or race, tend to have higher mobility.

Areas with less inequality – the Gini coefficient is the standard measure for this – have higher levels of mobility. This is consistent with the "Great Gatsby Curve". It is worth noting here that the income share for the top 1% is not highly correlated with intergenerational mobility. To ground this, imagine two societies with identical top-1% shares; the same handful of billionaires soaking up the same slice. But in one, there's a broad, healthy middle class with good schools, stable neighborhoods, and lots of rungs on the ladder between "poor" and "comfortable." In the other, the middle has been hollowed out into a sharp poor-vs-rest divide. The theory here is that the second society will have worse mobility, even though their top-1% numbers are the same. A hedge-fund manager earning $500M instead of $50M doesn't change much about whether a working-class kid can reach the middle, but the erosion of those middle rungs does.

Areas with proxies for better K-12 school quality – higher test scores, smaller classes, more spending per student, lower dropout rates – also tend to have higher intergenerational mobility. Kids from low-income families in those areas do better as adults, relative to their parents, than kids in areas with weaker schools.

Areas with proxies for the strength of social networks and community involvement – rates of religious involvement, participation in community organizations, voter turnout, the density of civic groups – are positively correlated with mobility. Areas that score higher on these community-connectedness measures also tend to have higher upward mobility.

Areas with fewer single-parent households tend to have higher upward mobility. Children of single parents do worse, on average, than children of married parents – for reasons tied to their own household (less income, less time, etc.). Add up a lot of single-parent households and the area's average mobility falls, simply because it contains more of the children who do worse. The prevalence of single parenthood in the surrounding area affects everyone's kids, even kids whose own parents are married.

In communities where children are statistically more likely to move up relative to their parents, these five factors – integration, reasonable equality in the middle, strong schools, thick social capital, and family stability – are the clearest signals the evidence offers about what works.

Charles Murray describes areas like these as "Super Zips" — the zip codes in the U.S. with the highest per capita income and college graduation rates. The above is not an argument for people to flock to Super Zips. Many people cannot or would not want to relocate to such areas.

Understanding this does not solve the harder problem of creating more such places. It does, however, clarify the geographic skew of the American Dream today.

I built a tool that ranks the ~800 Super Zips in America, based on household income, rates of college education and home values. You can access the tool at kennedyekezie.com/super-zips.