The “periurban” realm, whose rapid expansion since the 1960s has caused widespread concern, is difficult to grasp owing to its ambiguous nature, somewhere between urban and rural. Incidentally, the term “periurbanization” has only latterly gained currency in the French scientific community. It was the new geographic nomenclature of INSEE (Institut National de la Statistique et des Études Économiques – French Institute for Statistics and Economic Studies), elaborated in 1996 , that officialized the term, making periurban an official statistical category. Various other terms had been used before that: e.g. ZPIU (zone de peuplement industriel et urbain, industrial and urban population zone), previously used at INSEE from 1962, and rurbanisation, a neologism coined by geographers Bauer and Roux  to underscore the partial repopulation of the countryside in the context of a massive rural exodus. Deeming these terms inadequate to describe the rapid changes to French geography, the French ministry of agriculture, the Interministerial Urban Delegation and DATAR (Délégation Interministérielle à l’Aménagement du Territoire et à l’Attractivité Régionale – Interministerial Delegation for Regional Planning and Development), commissioned the Société d’Études Géographiques, Économiques et Sociologiques  (Society for Applied Geographic, Economic and Sociological Studies) to carry out a study aimed at refining the definition of what was to become, two years later, in the official nomenclature, the “periurban” zone. Nonetheless, the definition thereof is not entirely unproblematic, and it has a bearing on the very nature of the phenomenon that is to be measured. Various critiques of periurbanization reveal a wide range of different constructions put on the term itself.
Indeed, periurban areas are the object of recurrent critiques in public debate, whether cultural (apathy and individualism of periurban residents), aesthetic (uniformity of rows of detached houses to the detriment of France’s architectural heritage), economic (cost of dependence on the automobile for individual households and of public transportation for municipalities) or environmental (consumption of natural or agricultural land). The issue is clearly the rate of growth of these areas rather than their existence per se, which seems intrinsic to the urban phenomenon, as the very age of the suburbs suggests. So the INSEE’s new nomenclature should facilitate a better understanding of the evolution of periurban areas. According to this definition, periurban areas in 1999 comprised over 15,000 municipalities in France with a total population of close to 12.5 million inhabitants, or 22% of the French population, as against 19,000 municipalities and 10.5 million inhabitants in rural areas. However, after a period of rapid expansion in the course of the 1970s, the demographic growth of periurban fringes has apparently slowed down (+2.2% p.a. between 1975 and 1982 as against +1.3% p.a. since 1999) and the geographic spread of periurban zones, i.e. the distance from city centers, seems to be increasing only very slightly. The growth rates of periurban fringes, suburbs and city centers now seem to be increasingly converging .
Apart from the measurement of growth, the advantage of INSEE’s new urban zoning system, based on the 1990 census, is that it does a better job of taking into account the influence of cities on the surrounding countryside, particularly in terms of employment (“functional dependence”). This zoning breaks the country down into two basic categories: predominantly rural areas, made up of small urban units and rural districts, which cover more than two-thirds of France; and predominantly urban areas, made up of urban hubs (contiguous urban units providing at least 5,000 jobs) and periurban areas (periurban fringes and multipolar districts). According to INSEE’s definition, periurban fringes are districts in which at least 40% of the resident working population is employed outside the district, in the urban hub or in districts associated with the latter. The defining feature of multipolar districts is that they depend on several different urban hubs at once.
If we leave aside the societal debates over periurban areas – seeing as they are not the subject-matter of this article –, the terminology INSEE has chosen remains nonetheless controversial. First of all, like any statistical category, it involves a threshold effect that artificially separates districts in which at least 40% of the working population is drawn from other cities. Different thresholds in this case would probably have altered the periurban borders. However, INSEE does conduct tests of robustness to ensure that, at the 40% threshold, there is less variation. Other sociological issues also raise questions about the definition of periurban areas. Are home-workplace commutes the only commutes that inform periurban ways of life? In that case, how can one allow for commutes to service, shopping and recreational hubs? Moreover, for the resident population that does not commute back and forth, the area they experience is clearly not that of the agglomeration. Lastly, the periurban statistical category homogenizes areas that have nothing in common according to the size of the urban hub of reference (medium-sized, small city etc.). For example, the level of collective facilities or services, even the building density may vary considerably from one zone to another. For Eric Charmes , the definition of periurban ought to emphasize more qualitative criteria and admit of an approach based on geography and urban planning. Periurban districts are functionally (and symbolically) dependent on an agglomeration, but they are also marked by a high level of interpenetration with natural or agricultural zones as well as urbanized zones – in contrast to the suburbs – and by a low level of functional diversity and building density – in contrast to the city.
Lastly, the use of the term periurban by sociologists, but also by certain geographers, refers more to a way of life than to a geographic localization. The experience of those living on the periphery of agglomerations varies according to the size of the central district, but also according to the type of housing (small collective, spread-out individual or group housing etc.) and the income levels of the resident population. Between the periurban zone of the middle classes moving into local politics  and that of the “captives” of remote outskirts , there is precious little common ground in terms of urban, economic, cultural and political practices. By dint of social policies to facilitate homeownership, periurban areas are in fact socially diversifying thanks to the low cost of local real estate. According to Mischi and Renahy, the periurban actually constitutes “the only zone in which the working-class contingent did not see its numbers decline” between 1982 and 1999, “while over 76% of France’s management-level staff are concentrated in the city” . As a result, the periurban, which has partly become the place of residence of lower-income social strata, encompasses diverse social realities that raise questions about the pertinence of the periurban category in the first place. While “periurban” may ultimately prove insufficient to describe the evolution of cities and urban societies, it could still remain operational for local districts that bear part of the cost of this low-density urban sprawl.