We do not know

What do we know about cities? To simplify shamelessly,

1. The canonical model of urban economics predicts that cities will spread out as communications and transportation costs fall.  This has been the experience -- from pedestrian to streetcar to automobile city.

2. But the model leaves out many things. Nate Baum-Snow writes about these and suggests that outward expansion will stop or even reverse. Average densities will rise.

3. But we are now networked as never before, suggesting that the forces cited in #1 will pick up steam.

So which will it be?

Wendell Cox has recently posted results from his work on redefining metropolitan sub-areas. Adapting an approach similar to one developed by David L.A. Gordon and associates at Kingston University in Ontario, (and using zip code data re urban characteristics), Cox moves us beyond the very inadequate use of "central city" vs. "suburbs". These have relied on municipal boundary definitions of the "central city" and defining  the rest of the metropolitan area as the "suburbs".  But municipal boundaries have no functional usefulness and vary considerably in terms of the extent of their "footprint."  There is also room for confusion because some people construe "central city" as the downtown. Note also that any binary classification falls way short.

Using the refined definitions of "urban core," Cox calculates recent U.S. urban core population trends this way:

1990-2000   -1.164%
2000-2010   -1.110%
1990-2010   -1.137%

We know that the last two decades have seen the revival of many major U.S. downtowns (explained in large part by less crime); the most recent decade includes the extraordinary increase of electronic networking. But the data show no change. Have the two effects cancelled each other?  We do not know.

In this conversation, Russ Roberts and Mike Munger discuss the impacts of Uber, AirBnB, Monkey Parking and similar advances. Listen especially to the last segment. Just as Amazon went from selling books to selling everything, Roberts and Munger say "we ain't seen nothing yet."  The three technologies (and others on the way) help us to make much better use of the capacity we have.  Add driverless cars, and why own a car? or a garage? or a parking lost?  The word "transformative" is used in the conversation.

The years 2000-2010 are very early in the game. What will iPhone City look like? We do not yet know.