Introduction

Even if some large cities still have a monocentric structure (for example Paris, London, New York), plenty of others, especially in the United States, tend to be characterized by a more polycentric structure. Indeed, one of the most striking features of the American urban landscape has been the massive and continuous suburbanization of both people and jobs in the second half of the twentieth century. Whereas, on average, more than 57% of the Metropolitan Statistical Area (MSA) residents were located in a central city in 1950, the proportion of central city residents was already down to 40% in 1980 (Mieszkowski and Mills, 1993) and was still around 40% in the year 2000 (Anas, Arnott, and Small, 1998; Gobillon, Selod, and Zenou, 2003). In his famous book, Garreau (1991) coined the term “edge city” to describe this phenomenon of decentralization of jobs and families. This is related to the issue of urban sprawl (Brueckner, 2000; Nechyba and Walsh, 2004; Glaeser and Kahn, 2004). The emergence of edge cities and urban sprawl thus appears to be truly characteristic of U.S. cities and has major implications for the location of both jobs and people and their labor market outcomes. From a theoretical point of view, it is thus important to relax the assumption of monocentric cities and investigate to what extent multi-job centers affect the different results of Chapters 1 and 2.