Enrico Moretti

We're used to thinking of the United States in opposing terms: red versus blue, haves versus have-nots. But today there are three Americas. At one extreme are the brain hubs-cities like San Francisco, Boston, and Durham-with workers who are among the most productive, creative, and best paid on the planet. At the other extreme are former manufacturing capitals, which are rapidly losing jobs and residents. The rest of America could go either way. For...