A great deal of urban policy depends on the possibility of creating stable, economically and racially mixed neighborhoods. Many social interaction models - including the seminal Schelling (1971) model -- have the feature that the only stable equilibria are fully segregated. These models suggest...

The received economic wisdom is that cities are too big and that public policy should limit their sizes. This wisdom assumes, unrealistically, that city sites are homogeneous, migration is unfettered, land is given freely to incoming migrants, and federal taxes are neutral. Should those...