Aug. 29, 2005; Hurricane Katrina a Category 5 Storm with sustained winds of 145 MPH and gusts reaching 175 MPH is the most destructive hurricane ever to hit the United States. The storm caused massive devastation in and around the city of New Orleans with some of the worst problems caused when storm surges overwhelmed the city’s levees, flooding 80 percent of the city. Many questions were asked about the federal government’s slow response to the people of New Orleans when compared with the response to earlier hurricanes in Florida.

The timeline for Hurricane Katrina Events was the most costly natural disaster in American history, with damages of more than $80 billion. In all, more than 1,800 people died and despite efforts to rebuild the city, large parts of New Orleans still remain heavily damaged and many thousands have left the area and are unlikely to return.

Hurricane Katrina of the 2005 Atlantic hurricane season was the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall. At least 1,836 people lost their lives in the actual hurricane and in the subsequent floods, making it the deadliest U.S. hurricane since the 1928 Okeechobee hurricane; total property damage was estimated at $81 billion (2005 USD), nearly triple the damage wrought by Hurricane Andrew in 1992.
 
Hurricane Katrina formed over the Bahamas on August 23, 2005 and crossed southern Florida as a moderate Category 1 hurricane, causing some deaths and flooding there before strengthening rapidly in the Gulf of Mexico. The storm weakened before making its second landfall as a Category 5 storm on the morning of Monday, August 29 in southeast Louisiana. It caused severe destruction along the Gulf coast from central Florida to Texas, much of it due to the storm surge. The most severe loss of life occurred in New Orleans, Louisiana, which flooded as the levee system catastrophically failed; in many cases hours after the storm had moved inland. Eventually 80% of the city and large tracts of neighbouring parishes became flooded, and the floodwaters lingered for weeks. However, the worst property damage occurred in coastal areas, such as all Mississippi beachfront towns, which were flooded over 90% in hours, as boats and casino barges rammed buildings, pushing cars and houses inland, with waters reaching 6–12 miles (10–19 km) from the beach.

The hurricane protection failures in New Orleans prompted a lawsuit against the US Army Corps of Engineers (USACE) the builders of the levee system as mandated in the Flood Control Act of 1965. Responsibility for the failures and flooding was laid squarely on the Army Corps in January 2008, but the federal agency could not be held financially liable due to sovereign immunity in the Flood Control Act of 1928. There was also an investigation of the responses from federal, state and local governments, resulting in the resignation of Federal Emergency Management Agency (FEMA) director Michael D. Brown, and of New Orleans Police Department (NOPD) Superintendent Eddie Compass. Conversely, the United States Coast Guard (USCG), National Hurricane Centre (NHC) and National Weather Service (NWS) were widely commended for their actions, accurate forecasts and abundant lead time.
 
Nearly five years later, thousands of displaced residents in Mississippi and Louisiana are still living in trailers. Reconstruction of each section of the southern portion of Louisiana has been addressed in the Army Corps LACPR Final Technical Report which identifies areas not to be rebuilt and areas and buildings that need to be elevated.

As the eye of Hurricane Katrina swept to the northeast, it subjected the city to hurricane conditions for hours. Although power failures prevented accurate measurement of wind speeds in New Orleans, there were a few measurements of hurricane-force winds. From this the NHC concluded that it is likely that much of the city experienced sustained winds of Category 1 or Category 2 strength.

Katrina's storm surge led to 53 levee breaches in the federally built levee system protecting metro New Orleans and the failure of the 40 Arpent Canal levee. Nearly every levee in metro New Orleans was breached as Hurricane Katrina passed just east of the city limits. Failures occurred in New Orleans and surrounding communities, especially St. Bernard Parish. The Mississippi River Gulf Outlet (MR-GO) breached its levees in approximately 20 places, flooding much of east New Orleans, most of Saint Bernard Parish and the East Bank of Plaquemines Parish. The major levee breaches in the city included breaches at the 17th Street Canal levee, the London Avenue Canal, and the wide, navigable Industrial Canal, which left approximately 80% of the city flooded.

Most of the major roads traveling into and out of the city were damaged. The only routes out of the city were the westbound Crescent City Connection and the Huey P. Long Bridge, as large portions of the I-10 Twin Span Bridge traveling eastbound towards Slidell, Louisiana had collapsed. Both the Lake Pontchartrain Causeway and the Crescent City Connection only carried emergency traffic.
On August 29, at 7:40 a.m. CDT, it was reported that most of the windows on the north side of the Hyatt Regency New Orleans had been blown out, and many other high rise buildings had extensive window damage. The Hyatt was the most severely damaged hotel in the city, with beds reported to be flying out of the windows. Insulation tubes were exposed as the hotel's glass exterior was completely sheared off.

The Superdome, which was sheltering many people who had not evacuated, sustained significant damage. Two sections of the Superdome's roof were compromised and the dome's waterproof membrane had essentially been peeled off. Louis Armstrong New Orleans International Airport was closed before the storm but did not flood. On August 30, it was reopened to humanitarian and rescue operations. Limited commercial passenger service resumed at the airport on September 13 and regular carrier operations resumed in early October.
 
Levee breaches in New Orleans also caused widespread loss of life, with over 700 bodies recovered in New Orleans by October 23, 2005. Some survivors and evacuees reported seeing dead bodies lying in city streets and floating in still-flooded sections, especially in the east of the city. The advanced state of decomposition of many corpses, some of which were left in the water or sun for days before being collected, hindered efforts by coroners to identify many of the dead.
 
The first deaths reported from the city were reported shortly before midnight on August 28, as three nursing home patients died during an evacuation to Baton Rouge, most likely from dehydration. While there were also early reports of fatalities amid mayhem at the Superdome, only six deaths were confirmed there, with four of these originating from natural causes, one from a drug overdose, and one a suicide. At the Convention Center, four bodies were recovered. One of the four is believed to be the result of a homicide.