During major disasters, maps can provide vital information about at-risk regions. In the case of Hurricane Harvey, we added the locations of local Toxic Release Inventories (TRIs) to a map of Houston flooding. In rescue efforts, maps, similar to the one we created, allow officials to determine which areas of the city are in the most danger; analysts evaluate where the flooded regions overlap with or are within a short distance of TRIs. In our map, TRIs along Buffalo Bayou were closest to floods and posed the most risk. Once these areas are identified, administrators can decide which neighborhoods need immediate attention from rescue crews and clean-up organizations, which residents need to be evacuated, and where the water supply may be contaminated. By representing multiple relevant data sets on a single map, officials can analyze multiple hazards at once and make more effective disaster recovery plans.