The Act created the National Flood Insurance Program, offering federally backed flood cover in any community that adopted floodplain management rules: mapped special flood hazard areas, minimum first-floor elevations, and construction standards for new building. The Flood Disaster Protection Act of 1973 made purchase compulsory for federally related mortgages in those zones, which turned the Flood Insurance Rate Map into the effective regulator of American coasts and river valleys. The programme has run at a deep deficit since Katrina, Sandy and Harvey, borrowing tens of billions from the Treasury.
The United States answered flood risk with subsidised insurance plus local codes rather than prohibition, which underwrote half a century of coastal and floodplain suburbanisation while embedding the first federal building standards inside municipal ordinances. The FIRM line is now among the most consequential lines drawn on American land, governing mortgage availability, elevation, insurance cost and what may be rebuilt after a disaster.
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