Working Paper #811
Delineating urban areas using building density
Marie-Pierre de Bellefon · Pierre-Philippe Combes · Gilles Duranton and Laurent Gobillon
We develop a new dartboard methodology to delineate 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 smoothing to counterfactual smoothed building density computed after randomly 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 document the robustness of our approach and large differences between our preferred delineation and the corresponding official one.