When Hurricane Katrina struck the Gulf Coast as a Category 3 storm five years ago, it unleashed a series of events that took nearly 2,000 lives, destroyed an American city and devastated an entire region.
Katrina will never happen again -- the name has literally been removed from the World Meteorological Organization's list of storm names. But a storm with Katrina's size and power will almost certainly hit the Gulf Coast again in the future.
Politicians and government bureaucrats say they've learned from the mistakes of Katrina, but how prepared is Louisiana for the next big storm? What would happen to New Orleans if a major hurricane hit today?
An assessment of where things stand shows that the city is far better prepared to evacuate its citizens, but New Orleans' levee system is not yet fully prepared to protect the city from a big storm, and the natural defenses of coastal Louisiana are weaker than ever before.
Watch "World News with Diane Sawyer" for more coverage of our series, Katrina: Where Things Stand
After Katrina, the federal government made it a priority to rebuild the broken levee system, authorizing $12.8 billion in funding. Today, about $15 billion has been spent on levee reconstruction, but the system still can't protect all of New Orleans in the event of a 100-year storm, a hurricane with a 1 percent chance of occurring in any given year.
The Army Corps of Engineers says the massive project is on track to provide 100-year protection by the start of hurricane season next year. And if a hurricane like Katrina, a 400-year storm, were to hit today, authorities say the city would be in far better shape than it was in 2005. New Orleans would get wet, they say, but the levees would hold.
"The area of metro New Orleans that experienced so much flooding during Hurricane Katrina, we believe that with the systems that are in place right now, we wouldn't experience that same level of flooding," said Michael Park, the deputy director of the Army Corps of Engineers' Task Force Hope. "Certainly, with a storm the size of Katrina and the state of completion of the system ... we would expect to experience overtopping of some of the features around the perimeter."
The system was tested during Gustav, when waters did overtop New Orleans' industrial canal, but the flood walls remained in tact.
"Where the breaches occurred in the outfall canals during Hurricane Katrina, we've put in place interim control structures and pump stations that isolate those canals from storm surges," Park said.
If all goes according to plan, New Orleans levee system will not only provide 100-year protection by next year, but its barriers could handle the brunt of a 500-year storm.
"We're designing a level of resiliency into the system so that even for a storm that has a 0.2 percent annual chance of occurrence, we're building it so that the stillwater component of that storm surge would not overtop the levees or flood walls, it would only be wave overtopping," said Park.
One of the major problems of Katrina was a failed evacuation that left many of New Orleans' poor and elderly residents seeking shelter within city limits as the storm came ashore. Instead of evacuating New Orleans entirely, they remained in the city's shelters of last resort, like the downtown convention center and the Superdome, where conditions quickly devolved into misery.