In June 2020, the Environmental Protection Agency and the Army Corps of Engineers narrowed the definition of “Waters of the United States” (WOTUS), significantly limiting wetland protection under the Clean Water Act. Current policy debates and litigation center on the uncertainty around wetland benefits, especially concerning damages from flooding, the most costly and frequent natural disaster. Our study estimates the value of wetlands for flood mitigation across the entire United States using detailed flood claim and land use data. Employing three different identification strategies, we find that one ha of wetland provides $2,300 in annual flood mitigation value when accounting for spatial spillovers. Our results indicate that wetland loss between 2001 and 2016 increases flood claims by $535 million (or 19 percent) annually. The spatial heterogeneity we document in wetland benefits has implications for the WOTUS rule change affecting the 50 percent of “isolated” wetlands.