Hurricane Katrina
Hurricane Katrina made landfall in southeast Louisiana on August 29, 2005, as a Category 3 storm. The storm surge — up to 8.5 meters in some places — overwhelmed New Orleans' levee system. 80% of the city flooded. 1,833 people died.
Katrina was a Category 5 over the Gulf of Mexico with peak winds of 280 km/h. It weakened to Cat 3 by landfall, but the storm surge was generated when it was still Cat 5 — and storm surge takes hours to dissipate.
53 federal levees and floodwalls failed in 50 different places. Most were not overtopped — they collapsed from the *pressure* of water against substandard construction. The most catastrophic failure was at the 17th Street Canal, which breached around 9:30 AM CDT, flooding Lakeview within hours.
The federal response was widely judged a failure. The Superdome and Convention Center, designated as refuges of last resort, housed 30,000+ people for five days without adequate water, food, sanitation, or evacuation.
Total damage: $186 billion (in 2025 dollars). Katrina is still the costliest hurricane in U.S. history. The city's population in 2005 was 484,000; in 2025 it remains around 376,000 — Katrina permanently displaced roughly a quarter of New Orleans.