According to: F. Paulus (2002). Sources : INSEE – Censuses of the population and Ph. Julien (2001)
The spatial extension of the cities was thus considerably more rapid than the growth of the population they welcomed. On the periphery, the forms of urbanization were more and more diluted on the borders of the peri-urbanization zones, while to the contrary, a certain condensation was produced in the first rings of the periphery, those that are the closest to former suburbs, and which become integral parts of the agglomérations. In both cases, the process of peri-urbanization is combined with a process of reduction in the density of the resident population in the urbanized zones, which helps to explain the urban spatial diffusion.
The Process of Reduction in Population Density Whether measured in the setting of agglomérations or of aires urbaines, the densities of urban population have not ceased to decline since 1968 (Table 2). This decrease is slow, around 0.4% per year in the agglomérations, and irregular, with two phases of greater intensity near the end of the 1970s and the 1990s. In the setting of the aires urbaines, the strong initial density particularly reflects the fact that at that time they involved the largest cities (on an average, the densities rise with the size of the cities), and the rapid reduction in density reveals the gradual integration of smaller urban centres, and especially the numerous sparsely-populated rural communes.
The contrast in population density between the city centers and the peripheries has diminished in all the agglomérations of more than 20,000 inhabitants. However, in no city has a reversal of the center-periphery gradient been observed, either in population density or in terms of real estate and property values.
The process of spacing out is also measured by the inequalities in demographic growth observed in the various sectors of the aires urbaines according to present boundaries (Table 3). These illustrate an undulating spread in growth, initially greatest in the suburbs, then in the peri-urban rings beginning in 1975-1982, when the central communes were beginning a demographic decline. During the last decade, with the reduction in the general growth of the urban population, there has been a tendency for the intensities of growth in all the component parts of the urban population to converge.
Table 3: Demographic Changes in the City Centers, Suburbs and Peri-Urban Rings (1968-1999, 1999 Boundaries)
Average annual rate of variation in population (%)
Total of the Aire Urbaine
According to : F. Paulus (2002). Sources :Censuses of the population, INSEE
The spacing out of the urban populations has been perpetuated by the pattern of residential migrations, which have produced a centrifugal dynamic of populations, from the center towards the suburbs and the peri-urban ring. The peri-urban sector thus owes its dynamism to the populations that have chosen to establish themselves there. It is the opposite of the rise in births that made it possible to maintain the population of the centers, which a significant number of inhabitants were deciding to leave.
In total, the segment of the population of the aires urbaines living in the central communes has diminished at a regular rate, dropping from 46% in 1968 to 37% in 1999, while that of the suburbs has become preponderant, progressing from 38 to 42%, and that of the peri-urban rings has grown from 16 to 21%. The type of life we could call ‘rurban’ involves only about a fifth of the urban populations (figure 3).