most American cities do not need more affordable housing in their downtowns. Most American cities have too much affordable housing downtown. Or, more accurately, too much of their downtown housing is affordable, since everyone but the poor was able to join the suburban exodus. The typical midsized American city center now contains a few market-rate

as cities grow and their networks evolve, the area or volume of the networks needed to keep them functionally connected tends to become smaller on a per capita basis. For example, in larger cities more people can share the same bus or segment of road or sewer pipe.