A popular version of history trumpets the United States as a diverse "nation of immigrants," welcome to all. The truth, however, is that local communities have a long history of ambivalence toward new arrivals and minorities. Persistent patterns of segregation by race and income still exist in housing and schools, along with a growing emphasis on rapid metropolitan development (sprawl) that encourages upwardly mobile families to abandon older communities and their problems. This dual pattern is becoming increasingly important as America grows more diverse than ever and economic inequality...