Hurricane Katrina was a devastating Category 5 Atlantic hurricane that resulted in 1,392 fatalities and caused damage estimated between $97.4 billion to $145.5 billion in late August 2005, particularly in the city of New Orleans and its surrounding areas. At the time, it was the costliest tropical cyclone on record, tied now with Hurricane Harvey of 2017. Katrina was the twelfth tropical cyclone, the fifth hurricane, and the third major hurricane of the 2005 Atlantic hurricane season. It was also the fourth-most intense Atlantic hurricane on record to make landfall in the contiguous United States. Katrina originated on August 23, 2005, as a result of the merger of a tropical wave and the remnants of Tropical Depression Ten. Early the following day, the depression intensified into a tropical storm and headed generally westward toward Florida. On August 25, two hours before making landfall at Hallandale Beach, it strengthened into a hurricane. After briefly weakening to tropical storm strength over southern Florida, Katrina entered the Gulf of Mexico on August 26 and rapidly intensified. The storm strengthened into a Category 5 hurricane over the warm waters of the Gulf of Mexico before weakening to a high-end Category 3 hurricane at its second landfall on August 29 over southeast Louisiana and Mississippi. The majority of the loss of lives in Hurricane Katrina was due to flooding caused by fatal engineering flaws in the flood protection system, specifically the levee, around the city of New Orleans. Eventually, 80% of the city, as well as large areas in neighboring parishes, were flooded for weeks. The flooding also destroyed most of New Orleans's transportation and communication facilities, leaving tens of thousands of people who did not evacuate the city prior to landfall with little access to food, shelter, and other basic necessities. The disaster in New Orleans prompted a massive national and international response effort, including federal, local, and private rescue operations to evacuate those displaced from the city in the following weeks. After the storm, multiple investigations concluded that the U.S. Army Corps of Engineers, which had designed and built the region's levees decades earlier, was responsible for the failure of the flood-control systems. However, federal courts later ruled that the Corps could not be held financially liable due of sovereign immunity in the Flood Control Act of 1928. The emergency response from federal, state, and local governments was widely criticized, leading to the