New Orleans was catastrophically affected by what Raymond B. Seed called "the worst engineering disaster in the world since Chernobyl", when the Federal levee system failed during Hurricane Katrina on August 29, 2005. By the time the hurricane approached the city on August 29, 2005, most residents had evacuated. As the hurricane passed through the Gulf Coast region, the city's federal flood protection system failed, resulting in the worst civil engineering disaster in American history. Floodwalls and levees constructed by the United States Army Corps of Engineers failed below design specifications and 80% of the city flooded. Tens of thousands of residents who had remained were rescued or otherwise made their way to shelters of last resort at the Louisiana Superdome or the New Orleans Morial Convention Center. More than 1,500 people were recorded as having died in Louisiana, most in New Orleans, while others remain unaccounted for. Before Hurricane Katrina, the city called for the first mandatory evacuation in its history, to be followed by another mandatory evacuation three years later with Hurricane Gustav.