As Brad Pitt pointed out in Design:e2, dense, urban, walkable cities consume less energy per person than any other kind of environment. It turns out that all that walking keeps you skinny too. Researchers are finding that suburban dwellers are significantly fatter than their urban counterparts, primarily because they drive everywhere, even to the fitness club. "In a livable city, it should be possible and pleasant to reach restaurants, shops and entertainment on foot. Those who insist on riding bicycles should be able to do so safely and find bike racks on every street. An efficient subway or light-rail system not only makes it cheap and easy to get around town while legally drunk, it also provides more walking opportunities from home to station and station to destination." ::Sploid and here is a list of walkable American cities.