An 1878 map of New Orleans' settled areas shows that most of the city's 200,000 residents at the time clustered in a narrow swath along the Mississippi River, settling on the natural levees created by periodic floods.

It was still a good idea 127 years later. The city's old footprint corresponds closely to the small area that remained dry in the disastrous floods that came after Hurricane Katrina.

Indeed, the storm served up an unwelcome reminder that the city's expansive interior, pumped dry in the first few decades of the 20th century, is mostly reclaimed swampland. The killer storm essentially recreated what was here when Bienville founded the city in 1718.

"All this area that people developed, which depended on putting your faith in manmade objects, was truly wet," said Sally Reeves, president of the Louisiana Historical Society. "The idea was that you could control nature. You can control nature some of the time, but you can't control it all of the time."

Realists at heart

Early settlers, whose efforts to keep south Louisiana waters in check were often unsuccessful, didn't fight that reality. They founded the city on a high spot at a curve in the river, where flooding left behind sediment that raised the level of the soil.

"The idea was to locate a settlement at the first high ground above the mouth of the river," said Arnold Hirsch, a historian with the University of New Orleans. "They didn't find high ground, but they found higher ground."

It was high enough that it stayed dry most of the time. Though flooding was a constant problem, the water would drain away to the back swamp, leaving the city dry.