The Exurbs in the United States

Eric Charmes, octobre 2015

In the United States, some researchers use the term exurbs to designate suburban residential areas inserted into a rural environment and thus physically detached from the urban area on which they depend. These areas are of less interest than in France. However, they are not ignored. They have received renewed attention with various publications making the exurbs key territories in keeping the Republicans in power during the 2004 presidential elections.

In this context, the Brookings Institution has funded research to quantify the demographic weight of the exurban rings. This work is all the more interesting in that, unlike many other studies conducted in the United States, the basic unit used to categorize urban areas is not the county (whose average population is around 100,000) but the «  census tract ", i.e., a unit with a population varying between 1,500 and 8,000 inhabitants, which is a scale close to that of French peri-urban municipalities. The exurban population then amounts to 10% of the population of metropolises with more than 500,000 inhabitants (Berube et alii, 2006). The phenomenon is therefore not negligible, even if it remains lower than in France.

The comparison is, however, delicate because the criteria used by the Brookings Institution to define the exurbs are different from those used by INSEE to define the peri-urban character of a commune. First, it is sufficient that 20% of the inhabitants of a sector (census tract) work outside the sector and in a conurbation for this sector to be qualified as exurbs. This threshold is less restrictive than the one used by INSEE, although it applies only to people working in the equivalent of the urban pole and not in the entire urban area (in other words, the exurbs are defined here in a single step, i.e., without iterative extension of urban areas). Moreover, Brookings Institution researchers have applied minimum density criteria to define «  exurban  » (as indeed would be desirable for INSEE to do).

Above all, unlike France, these exurbs constitute much larger urbanization nuclei than the units of the order of a thousand inhabitants formed by the French peri-urban communes. And, except in special cases, these nuclei are generally destined to expand and not to remain villages. In other words, unlike their French counterparts (see Des villes qui s’étalent en s’émiettant), many American exurbs are destined to join the suburbs and feed the sprawl.

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