THE rhythm of the water was so gentle, and the view of the city so appealing, that I was not listening closely to the guide. But one thing I remember, as we churned down the Mississippi in a painted paddle steamer, was his pride in the flood defences protecting New Orleans.
The shock of Katrina lies not just in the force of the hurricane and the uncalculated loss of life. This city, fiercely loved by its inhabitants, is cherished by Americans as an enclave of hedonism. It is where graduating college students go to drink themselves stupid, or hip honeymooners to sample some jazz. With its palm trees and exotic French origins, New Orleans is a natural destination for visitors who want to let off steam.
Or was. Now that the stumbling evacuation is gathering pace, a town with a similar population to that of Edinburgh's will be shut down, or left to looters and corpses. A place that was a byword for music and vitality will fall silent, aside from the whirring of choppers and the roar of bulldozers.
What will linger is the memory of the terrible days after the hurricane, when the world's superpower could not save its own citizens. Mellow New Orleans descended into savagery, from the shots fired at rescue teams to the reported rapes and murders inside the Superdome.
The image of another city floats above the floodwaters. When looting broke out in Baghdad after the Americans arrived, it was read as the anarchic response of people whose self-discipline had been sapped by totalitarian rule. Yet the same response surfaced in free and democratic America. The stories of blockaded hospitals, gunmen in the streets, fights over aid and policemen turning tail came not from Baghdad but Louisiana.
Iraq haunts Katrina's aftermath. It has already been invoked, politically if not morally. Where was the National Guard when it was needed? Were federal funds diverted to the war, after experts predicted that a hurricane in New Orleans could be a national disaster? As a military convoy arrived with aid on Friday, the general told his troops to lower their guns, adding, "This is not Iraq".
Americans take pride in being able to look after their own, and the last few days have damaged that self-image. For the hurricane has hit the most vulnerable people in the US. Louisiana, along with neighbouring Mississippi, is one of the poorest states in the Union. On virtually every indicator - personal income or employment, gun crime or high school drop-outs - they come near the bottom of the list.
About a third of the population in both states is black, including many of the poorest in New Orleans, who did not have cars and could not leave the city. Many of the looters caught on film were black, but so were some of the police who tried to keep order, and the mayor who warned last Sunday that people should leave town.
The romance of New Orleans has obscured the economic state of the region. Roads in Louisiana are bumpy and badly maintained. School buses drop off children at trailer parks. Refineries along the Mississippi spew out emissions that would be forbidden under EU law, even before the toxic leakages caused by Katrina. Mississippi, despite flashes of southern charm, also feels like a place that is down on its luck. Towns that were the backdrop for 1960s films like In the Heat of the Night are economically hollowed out, with people working at two jobs or no jobs. The casino ships destroyed in Gulfport and Biloxi were among the few steady earners.
How these areas will cope with thousands of refugees is hard to imagine. The first busloads went to cities in big-hearted Texas, which can afford to be generous. But other southern states volunteering help, like Arkansas and Alabama, are not much better-off than their neighbours.
After the horror of the last few days, the political and media narrative will switch to the relief effort. To fill the heart of darkness that opened up in New Orleans, there will be stories of kindness from strangers. To counter the charge of a slow and feeble federal response, the focus will shift to brave rescues and efficient logistics.
These accounts should not be seen merely as spin. There will be a demand for good news from a shocked US public, and an outpouring of support in a country where philanthropy often takes the place of social safety nets. Websites are packed with offers of free housing, from California to Michigan. Companies are donating flights, clothes and food.
But will it be enough to blot out images of survivors holed up in hotels and hospitals, frantically texting for help that never came? The backlash has started, coming not from idle tongues in Washington but from desperate voices on the ground. "Who will help us?" asked the editor of a local paper in Biloxi. "God is looking down on all this," said Ray Nagin, mayor of New Orleans, "and if they are not doing everything in their power to save people, they are going to pay the price."
The question is who "they" are and what the price will be. Bush is the obvious target for blame, but may yet deflect it. Bashing the federal authorities is an American habit, and a shrewd president can rise above the fray. Assorted national agencies came in for criticism after 9/11, yet little of it rubbed off on Bush.
Then there was an enemy, however. This time the enemy was the weather. While this is a religious country, Americans are not fatalistic as a people. They believe that anything is possible. So they will find it hard to accept that more could not have been done to prepare for the hurricane, especially when the sheer numbers of the dead become apparent. What will be even harder to accept is that survivors have died from lack of food, water and medical treatment.
The President, in his second term, can lose his reputation but not his office. Nor does the issue lend itself to party politics. While both states voted for Bush last year, Louisiana has a Democrat governor and New Orleans a Democrat mayor.
Once the blame has died away, Katrina's effect on public opinion is likely to be contradictory, intensifying mistrust of officialdom while heightening a sense of social interdependency. The scenes in New Orleans showed how fragile the social fabric of urban America can be under pressure from guns and drugs. The people of the city did not need rescuing just from the floods, but from each other.