Walkable cities have been around for centuries, but Leinberger argues that after the rise of the automobile, planners and real estate developers hit on the lucrative suburban strip-mall formula and stuck to it.
"For 50 years we had this collective amnesia about how to build great places," said Leinberger, whose institution describes itself as a nonprofit public-policy organization.
The New York area had the highest number of walkable urban places in Leinberger's survey. Most of the 21 places he listed are neighborhoods in Manhattan.
But the Washington region, with 20 walkable places, outranked New York on a per-capita basis, and Leinberger says it could serve as a national model. It has one walkable place for every 264,000 people.