[It] is sentimental and romantic to assume that any education or any example will ever completely destroy the inclination of human nature to seek special advantages at the expense of, or in indifference to, the needs and interests of others. ~Reinhold Niebuhr Spatial geographers and demographers tell us that segregation occurs whenever the proportions of two or more populations are not homogenous throughout a defined space. Plant and animal species are therefore usually—but not always—segregated; people, too, in societies throughout the world, are usually—but not always—segregated according to language, cultural difference, religion, nationality, educational background, political allegiance, and socioeconomic status. To be sure, none of this means that demographic patterns are fixed. Empirical evidence shows,1 for example, that American suburbs are more diverse than ever; recent evidence from England and Wales, too, suggests that ethnic mixing in neighborhoods and schools is increasing rather than decreasing.2 Rates of mixed marriages and cross-cultural exchanges, too, have everywhere increased. Yet one can acknowledge these demographic developments and still plainly observe that spatial configurations of segregation are everywhere recognizable; …