Pierre-Philippe Combes is CNRS research professor of economics at the Université d¹Aix-Marseille. Thierry Mayer is professor of economics at the Université Paris 1 Panthéon-Sorbonne. Jacques-François Thisse is professor of economics at the Université Catholique de Louvain and professor at the Ecole Nationale des Ponts et Chaussées. His books include Economics of Agglomeration.