Wednesday, October 01, 2014

High or low densities?

Urban economists and urban planners love "density". I put it in quotes because the details (How high? Where? At what cost?) are often ignored. The argument is simple. New ideas prompt productivity and growth. We form new ideas when we interact with others. Higher densities prompt higher volumes of encounter and interaction. 

But there is also the problem that the dominant trend has been to lower average densities. See, for example, Bruegmann's indispensable book. 
“Most American anti-sprawl reformers today believe that sprawl is a recent and peculiarly American phenomenon caused by specific technological innovations like the automobile and by government policies like single-use zoning or the mortgage interest deduction on the federal income tax.  It is important for them to believe this because if sprawl turned out to be a long –standing feature of urban development worldwide, it would suggest that stopping it involves something much more fundamental than correcting some poor American land-use policies.  In the following chapters I will argue that the characteristics we associate today with sprawl have actually been visible in most prosperous cities throughout history.  Sprawl has been as evident in Europe as in America and can now be said to be the preferred settlement pattern everywhere in the world where there is a certain measure of affluence and where citizens have some choice in how they live.” (p. 17)
 At the level of the urbanized areas, the U.S. trend has been towards lower average densities. Considerable detail (courtesy of W. Cox) is available here and here.

I have mentioned previously that my fromer student Chen-Yi Lin looked at U.S. talent migration at the sub-metroplitan level (the PUMAs) and found considerable complexity in terms of the many densities that attract smart and credentialed people (Lin, C.Y. (2013). Talent migration: Does urban density matter?, Unpublished doctoral dissertation, Los Angeles: University of Southern California). Collaboration opportunities are available in all sorts of places -- and in many ways.

The American Community Survey data show that "work at home" has risen steadily, from 3.2% of all workers in 2000 to 4.4% in 2013. Still small but the public transit industry commands many billions of dollars of annual subsidies and cannot touch this rate of growth. I would say that the trends we see facilitate collaboration and innovation at many densities -- including low densities.