You might speculate that these studies merely demonstrate the city’s power to sort people by their preferences: Maybe Manhattanites walk because they are walkers, while Atlanta’s big-lot suburbanites and Canada’s power-center pilgrims drive because they prefer the air-conditioned comfort and storage capacity of the family minivan. In other words, just because urban designs correlate with travel behavior, it doesn’t mean they cause it.
This view is partly true. People do self-sort in cities. In Atlanta, for example, Frank found that people who said they preferred to live in car-dependent neighborhoods tended to drive pretty much everywhere, no matter where they lived. Not surprisingly, people who both liked and lived in lively, walkable places drove less and walked more. But the suburbs were full of people who wished they could walk places but couldn’t. Nearly a third of people living in Atlanta’s car-dependent sprawl wished they lived in a walkable neighborhood, but they were mostly out of luck because Atlanta had gone nearly half a century without building such places.