"People didn't really think Katrina would hit," said historian Doug Brinkley. "Everybody watched the blob on their TV screens and many residents, included myself, said you know what? I'll wait it out."
It turned out to be a huge mistake. In the Lower Ninth Ward and St. Bernard Parish, levees lining the area couldn't withstand the storm surge from Lake Ponchartrain. Along the Industrial Canal, concrete walls were breeched by water surging over the top and undermining shaky construction underneath. Pumping stations designed to serve as backup failed.
The New Orleans Superdome, where many fled on their own, became both haven and hell. The weakest of the weak perished, and the government couldn't help. Now it appears, Gustav will not be history repeated.
Last time, the National Guard lost many of its choppers and water vehicles to the same flooding. This time, the staging areas are outside of New Orleans.
And unlike the post-Katrina days there's been very little looting. Law enforcement on the streets of New Orleans has almost doubled.
And the infamous levee system along Lake Pontchartrain, where the three most serious breaches occurred, have undergone some repairs. The holes have been fixed and strengthened, the walls have been built up an additional three feet, and new pumps have been installed for better drainage.
A lot has gone right but there are things you simply can't predict. Two naval ships scheduled to be scrapped and a barge came untethered in the canal and there is real fear one could knock a whole in this levee. As you can see, water is already spilling over the top. That's why experts caution it's too early to say New Orleans has dodged a bullet.
There are still miles of levees along the coast that are so poorly built and stressed - Brinkley calls them "lego levees" - and protective wetlands still need to be restored.
"But to pretend that New Orleans is fortified is untrue. If this was a Category 5, it will not survive," Brinkley said. "New Orleans is still a very dangerous place to be during a hurricane."
That's a theory that wasn't truly tested by Gustav, but could be … next time.