Frederick Jackson Turner had it easy. The historian forecast the end of the American frontier--and then he died. Dan Burden is left with the complicated reality of a country not just short on frontier but seemingly out of space altogether. Even in midsize cities and 'burbs, traffic congestion can be so extreme that a walk to the market is impossible, biking downtown a flirtation with death. Burden, director of the High Springs, Fla., nonprofit Walkable Communities Inc., has figured out what to do. He's the guy people call to get their space back.
Burden, 58, puts bloated thoroughfares on what he...