Delineating urban areas using building density Marie-Pierre de Bellefon* † Pierre-Philippe Combes*§ insee, Paris School of Economics University of Lyon, cnrs, and Sciences Po Gilles Duranton*‡ Laurent Gobillon*¶ University of Pennsylvania Paris School of Economics, cnrs 27 October 2018 Abstract: We develop a new dartboard methodology to delin- eate urban areas using detailed information about building location, which we implement using a map of buildings in France. For each pixel, our approach compares actual building density after smooth- ing to counterfactual smoothed building density computed after ran- domly redistributing buildings. We define as urban any area with statistically significant excess building density. We also define the urban cores of these urban areas in a similar manner. Finally, we develop novel one- and two-sided tests to provide a statistical basis to compare maps with different delineations, which we use to docu- ment the robustness of our approach and large differences between our preferred delineation and the corresponding official one. Key words: urban area definition, dartboard approach, Jaccard indices jel classification: c14, r12, r14 *This work is supported by the Zell Lurie Center for Real Estate at the Wharton School. We appreciate the comments from Miquel-Angel Garcia-Lopez, Tomoya Mori, Esteban Rossi-Hansberg, Elisabet Viladecans, and participants at conferences and seminars. The views expressed here are those of the authors and not of any institution they may be associated with. †insee and Paris School of Economics, 48 Boulevard Jourdan, 75014 Paris, France (email:
[email protected]). §University of Lyon, cnrs, gate-lse umr 5824, 93 Chemin des Mouilles, 69131 Ecully, France and Sciences Po, Economics Department, 28, Rue des Saints-Pères, 75007 Paris, France (e-mail:
[email protected]; website: https://www.gate.cnrs.fr/ppcombes/).