Over the past few years, liberals and conservatives have been arguing over which growth model is best. But, of course, there’s no need to choose. Both models are more or less working.

What we’re seeing, it seems to me, is a profusion of economic growth models in different parts of the country — a net increase in economic pluralism and diversity. Perhaps even more than in the past, cities are specializing, turning into global hubs for a specific economic sector.

This diversity is an enormous economic advantage for the country, and an enormous social and political challenge. As the country diversifies economically, it segments socially and politically. Each economic sector attracts different kinds of people and nurtures different kinds of values. The specialization of output means that every place becomes more like itself.