The expectation of riches was the reason French explorers spent more than three decades searching either side of the Mississippi River, from Canada south to the Gulf of Mexico, before claiming all the land drained by the river and its tributaries. They named the territory Louisiana for King Louis XIV.
These explorers created settlements along the Gulf Coast such as Biloxi and Mobile, before Jean Baptiste Le Moyne, Sieur de Bienville, founded La Nouvelle Orleans in 1718. He chose this particular bend in the Mississippi because it would:
allow the French to control traffic on the river, levying taxes on all goods headed to or from the nearby Gulf of Mexico.
enable the French to prevent the hated British and Spanish from using the river to further their settlement of America.
cut days off shipment times between the river and the gulf via the vast bay called Lake Pontchartrain.
To bolster their claim to the land, the French sent thousands of settlers - free men, indentured servants and slaves from Africa - mainly to raise indigo and rice for European markets.
They suffered constant hardships, such as inadequate food and shelter. They also endured hurricanes and floods.
For millennia the river had deposited silt that created natural levees along its banks. Parts of New Orleans were as much as 12 feet higher than the river.
"But even in the 1720s, property owners were required to build walls to protect their land from floods," says Craig E. Colten, a Louisiana State University professor of environmental geography. Colten has spent about 20 years studying the hazards mankind creates for itself in choosing where to live.
In his book, An Unnatural Metropolis, Wrestling New Orleans From Nature, Colten writes that because much of the city is "below sea level and collects whatever water is not pumped out, managing the surplus fluid is critical (and) keeping the city dry . . . has been the perpetual battle for New Orleans."
Yet for centuries, private property owners and public officials were too shortsighted to realize they were working against their best interests in this war. Only in the past few years have researchers and government officials made a concerted effort to understand, and publicize, the increased potential for catastrophe multiplied by unchecked development.
"While those early settlers were (building their 3-foot levees mainly) on the southwest side of the river," Colten said by phone from his Baton Rouge office last week, "for about a century any floods could overflow to the east." That water drained in wetlands or flowed into the Gulf of Mexico bay named Lake Borgne.
But once significant levees were built on the other side of the river, Colten said, "the floodwaters that used to overflow for maybe 100 miles in that direction now had a channel no more than 2 miles wide, just between the levees."
Most of this development came in the 19th century, when the land was bought by the United States. Again, it was a decision based on money - eliminating the tariffs on river commerce - that led President Thomas Jefferson to offer to buy just New Orleans and some surrounding lands in 1803. Instead, the fledgling United States virtually doubled in size when cash-strapped Emperor Napoleon sold much more in what became known as the Louisiana Purchase.
In a little more than a decade, settlers by the tens of thousands headed for the fertile farmlands around New Orleans. The new state's population soared from 153,407 in 1820 to 352,411 in 1840.
With the state's successful cotton and sugar plantations and river commerce in tobacco, meat, and grain, by 1860 New Orleans was the nation's second-richest port, behind New York.
"New Orleans had repeatedly flooded," including in 1849 and 1867, "but from its inception, there were strong economic incentives to stay," says Carl A. Brasseaux, director of the Center for Louisiana Studies at the University of Louisiana at Lafayette. "Nothing was going to chase those settlers away."
As the city grew, developers dug canals for drainage. But these were inadequate; mosquitoes from city swamps caused 23 outbreaks of yellow fever between 1817 and 1860. The epidemic in 1853 killed more than 8,000 people.
Finally in the 1890s, during a post-Civil War economic recovery, the city government began constructing a canal system to remove water from the bowl created by miles of man-made levees. With the addition of pumps, this drainage and protection system held up well against Mississippi flooding.
But two torrential rainfalls in 1927 showed the system was inadequate to drain the much larger city. While the failure was obvious, there weren't hydrologists or ecologists around to warn against the ongoing draining of marshland that separated Pontchartrain from the river. The paving over of this area eliminated wetlands that had soaked wind-driven water off the lake before it reached the levees and the city.
The city and Army Corp of Engineers tended to the levees - major improvements in 1973 included concrete facings - and improved New Orleans' drainage-pumping system. It now can remove about 2 inches of standing water per hour.
The flip side is that the levees, and several canals from the Mississippi to the gulf dug since the 1940s, have served to speed the river's flow to the gulf. The result is that the Mississippi no longer leaves tons of sediment each year that had developed into wetlands at the river's mouth.
Brasseaux and Colten emphasized the importance of the loss of 25 to 30 square miles of coastal wetlands each year. "They used to be a sponge, absorbing the rain and wind of hurricanes blowing in from the gulf," Colten said.
Instead, such hurricanes not only add water to Pontchartrain, but also blow its waves against the city's drainage canals and levees. This sort of pounding during Katrina caused breaks in two canals, creating the massive flood that swamped much of New Orleans.
Even if there were electricity to power the pumps, Colten said he has heard it could take as long as four weeks to drain city streets.
Asked what he thought city, state and federal governments are likely to do to guard against another such catastrophe, Colten cited the past to predict the future:
"After every calamity, they have always built to face the most-recent bad flood, not for something worse. . . .
"So they are likely to improve the levees to accommodate another Katrina - and, hopefully, we won't get a Category 5."