Something new is appearing on the American landscape. Architects, planners, and others have given it a variety of names-spread city, slurb, exurb, edge city, sprawl. The profusion of vaguely ominous names is only one sign of our deep uncertainty about what this new thing is. Is it merely the old suburb swollen beyond all proportion? Or are we seeing the distinction between city and suburb gradually being erased? Historian Robert Fishman believes that a "new city," utterly without precedent,...