The Shape of Regulation: 40 Years of Florida Flood Maps

Many regulations are geographically targeted. We study the evolution of the spatial targeting of floodplain regulation over four decades of regulatory map updates in Florida. We focus on changes in shape irregularity of regulated areas, measured using differences between regulated polygons and their convex hulls. While the regularity of mapped polygons is uncorrelated with development in initial maps, we observe decreases in regularity over time concentrated in highly developed geographies. These changes are uncorrelated with changes in risk due to adaptation. Our results highlight the possibility of endogenous regulation and the value of leveraging historical maps for empirical analysis.