by Nicholas Beaudrot of Electoral Math
If I might take another crack at allaying Ross Douthat's fears we New Urbanists will come to take away his foot massager, no one seriously thinks that the goal of the shift from pro-sprawl policy towards a more balanced approach should be to turn every urban core into Philadelphia, let alone New York City. But lots of American cities have plenty of space for in-fill. The most dense post-automobile city (not including the suburbs) in America is Seattle, at 6,900 people per square mile. Yet you can still find single family, unattached houses inside the city limits at a price below the county's median home value. In a number of neighborhoods you could easily knock down two houses and put up three smaller houses on the same lot. Even without increasing density, Seattle has roughly the density of Frankfurt Germany, which has what looks like a six- or seven-line transit system. Getting Seattle to a mere three transit lines would make a big dent in the city's car usage and CO2 footprint. Families would probably still need to own a car, but they wouldn't need to use their car for every errand or trip to work.
As you go further down the ranks of density, you find cities that could withstand an awful lot of in-fill. Phoenix, AZ has a density of 2700 people per square mile; I'd be willing to bet there are farming villages in Italy with a higher density. Going beyond the city limits, there's wide variation in the density of suburbs; pushing "inner suburbs" to a somewhat denser arrangement would give a lot of people shorter commutes. Yes, some houses would go from a three-car garage to a two-car one, and a couple of rooms in the house might get a foot or two smaller, but a little moderation in home and lawn size wouldn't lead to the end of the world.
