Many retro-urban theorists maintain that high density is the key to urban prosperity. These theorists often point for justification to Santa Fe Institute research that, they claim, links productivity with density. Yet in reality it does nothing of the kind. Instead the study emphasizes that population size, not compactness, is the decisive factor.
Size does matter. A region is helped by the infrastructure that generally comes only with a large population, for example airports. But being big does not mean being dense. In fact the U.S. cities that made the largest gains in GDP in 2011 — Houston, Dallas-Fort Worth and greater Detroit — are not dense cities at all.
Some of the metropolitan regions that have the highest per capita GDPs in the world based on purchasing power are not particularly dense. The two regions at the top — Hartford, Conn. and San Jose, Calif., — are, if anything, largely suburban in character. Neither has a strong central core and most of the jobs in the areas are on the periphery.