A new study by the urban economist Issi Romem of BuildZoom looks at how America has grown, and the trade-offs that come with either continuing urban sprawl or opting for added density. Using data from the survey, CityLab's Richard Florida presents the reasons that creating denser cities is so difficult.
The data from Romen's survey looks at two different versions of growth: “expansive” and “expensive” cities or metro areas. “Expansive cities” as their name implies, have sprawled outwardly and in doing so remained largely affordable. “Expensive cities” are more hemmed in by geography and have not been able to expand nearly as much, and have seen their housing prices increase as a result.
A metro can still "sprawl" without adding to its footprint by developing the majority of it's housing in low-density areas. Florida explains: The overwhelming majority of new homes built across the country since the 1940s (90 percent of them) have been developed in low-density areas. In the 2000s, nearly a quarter (23.3 percent) of all new homes built were built in undeveloped areas, a third (33.2 percent) were built in areas with a prior density below one home per acre, and another third (31.9 percent) were in areas with a prior density between just one and four homes per acre.
The bias for sprawl stems from the fact that it's much cheaper and easier to build new housing in outlying areas of a city than it is to add to an already built-up area.
While most urbanists—including Romem—think sprawl is bad, it does offer communities a way to deliver both affordable housing and preserve their urban neighborhoods. The downside here, of course, is increased congestion and environmental degradation. Alternatively, metros that choose to limit sprawl and densify can make housing more affordable, but that can also come at the expense of character and “charm” of their existing urban neighborhoods.