Employment Density in Ile-de-France: Evidence from Local Regressions

In recent decades, cities have experienced a particularly intense phase of urban sprawl. Urban growth has been characterized by the spatial concentration of population in urban areas and the concomitant extension of those urban areas (Nechyba and Walsh 2004). Urban sprawl has also been accompanied by major reorganizations of urban areas with regard to the location choices of households and firms. More specifically, most cities in developed countries have experienced several waves of suburbanization of economic activities: “an economic definition of suburbanization is a reduction in the fraction of a metropolitan area’s population or employment that is located in the central city (corresponding to increased activity in surrounding suburbs)” (Mills 1999). Suburbanization of economic activities has an impact on urban structure: cities are not exclusively organized with a Central Business District (CBD) around which land values, employment, and population densities decrease with distance. On the contrary, they are more and more characterized by a polycentric organization: employment is concentrated in several centers within urban areas. Strategic activities (headquarters and high-order producer services) play a major role in this process by locating themselves selectively in these various centers. The development of peripheral employment centers – where a significant proportion of these activities are located, reproducing the functions of the CBD – is accordingly viewed as the decline of the CBD (Stanback 1991).