Housing Supply, Property Insurance, and Exposure to Wildfire Risk

In the past two decades, about half of the new homes in the United States were built in areas at risk of natural hazards. Why is residential development exposed to such risk? I argue that regulated property-insurance pricing and land-use regulations contribute to this pattern. I study this mechanism in the metropolitan area of San Diego, California, where insurance rules compress the premium gradient with respect to wildfire risk and safer locations are highly regulated and built out. Using detailed spatial data on zoning, wildfire risk, housing, commuting, and premiums, I estimate a quantitative urban model of household location choice, housing supply, and insurance supply. The estimates imply that wildfire premiums are 10.5% below actuarially fair pricing, that the average amenity cost of current wildfire risk is equivalent to 3.5% of income, and that the total present-value welfare cost of current wildfire risk, including property damages, is $17.5 billion. This aggregate cost masks substantial incidence heterogeneity, as owners of safe land benefit from equilibrium scarcity effects. Counterfactuals show that housing supply and insurance pricing interact in determining incidence. In the benchmark specification, targeted housing reforms leave the aggregate effect of cost-based insurance nearly unchanged while attenuating its burden on workers: relative to baseline, workers' wildfire costs rise by 2.3% under insurance reform alone, but fall by 0.9% under the joint reform.