There are only six American downtown districts that are dense enough to support mass transit, which you need if you’re going to be carless: New York City (Midtown and Downtown), Chicago, Philadelphia, Boston and San Francisco. That’s it. The breaking-point for density and mass transit feasibility seems to be about 50 persons per acre, which means families living in flats and apartments, rather than single-family houses, even row houses. Not necessarily high-rise apartments, but at least walk-ups.
Other contributors to the discussion include: D.J. Waldie, author of “Holy Land;” Dolores Hayden, professor of architecture; Christopher B. Leinberger, real estate developer and author; Alex Marshall, transportation columnist, Governing magazine; J.H. Crawford, author of “Carfree Cities;" Marc Schlossberg, professor of public policy