Rarely have cities avoided congestion; even ancient Rome was jammed with chariots and oxcarts. Yet today the world's cities are being drastically reshaped by the automobile, that super-congestor and enemy of pedestrians. The car has thrust high-speed freeways through downtown areas; it has squeezed city dwellers onto narrow sidewalks and into motorized suburbs. Worst of all, 60% of urban smog is caused by motor-vehicle exhaust.
All the same, autos need not destroy cities—as evidenced by a new revival of car-free malls, which could conceivably return the streets to the people. In cities like...