In ceremonies outside City Hall, in the great Catholic cathedral of St Louis in the presence of a president, and by the 17th Street canal where the calamity began - New Orleans came to a halt at precisely 9.38am yesterday to remember the moment when the first levee broke and the city was changed forever.
Out by the canal, they read the names of 32 people who died the day Katrina struck, casting a pink rose into the water for each one. Briefly, the teams of engineers who had been labouring night and day for months to repair the city's defences stopped work.
New Orleans has had nothing but difficult days since that terrible morning of 29 August, 2005, and this first anniversary was another of them. "We're going to get through today," Ray Nagin, the Mayor, told New Orleans' assembled elders, before ringing a silver bell outside City Hall to mark the precise moment of disaster. "And then I hope that everyone will turn their attention to rebuilding one of the greatest cities in America. If we work together, we can do it."
Thus the National Day of Remembrance unfolded, with speeches and prayer meetings, vigils and assemblies, with memories private and public, even a traditional jazz funeral procession, weaving its way between the Convention Center and the Superdome, buildings that now symbolise the chaos and misery of the days after the storm.
New Orleans was not the only victim of Katrina. Across devastated swaths of coastal Louisiana, Alabama and Mississippi, ravaged communities, great and small, held their own ceremonies - starting at the fishing village of Buras, 65 miles to the south-east, where the hurricane made landfall at 6.10am a year ago.
But New Orleans is the name with which Katrina will forever be linked. Other towns were levelled or washed away. None however bears such psychological scars, and none will be so hard to rebuild, both physically and spiritually.
Even for this most fatalistic and enduring of cities, the storm of a year ago was too much. A study published yesterday found that four out of five of its inhabitants suffered great personal or financial hardship, and that half of them still have nightmares about Katrina. The fatigue, the sense of living on the edge and of nerves rubbed to the raw, are palpable.
Nor was it an easy day for George Bush, on his 13th trip to New Orleans, where he and First Lady Laura bowed their heads in homage during a mass at St Louis Cathedral, reflecting on a disaster that changed not only the face of a city but the course of his presidency.
Naturally, the oratorical promises of renewal abounded. Speaking at a local high school, the President admitted the mistakes of a year ago. But he said, "We're better prepared now," pointing to the nonstop work on the levees, and the storm-proofing of the pumping stations that were overwhelmed a year ago. Once again, he pledged unstinting government support for the rebuilding.
"New Orleans is going to rise again," Mr Bush declared. A year from now, the city would be living "a golden age of entrepreneurialism".
Alas, today's reality is different. There are shortages of skilled workers, and wrangling over insurance and over the allocation of reconstruction funds, even over whether certain areas should be rebuilt. In other words, should New Orleans be permanently downsized, making it a whiter - probably more Republican - city? Such issues of race and politics are largely unspoken, but no less tangible for that.
Sometimes yesterday, you could see the frustration and anger. "Where was Fema [the federal government disaster agency]?," read placards carried by marchers in the Lower Ninth Ward, the poor area east of downtown where, a year on, electricity and other basic services have not been restored, even in areas which are habitable.
But this was not a day about a visiting President, or even about how to spend the $110bn allocated by Congress to deal with the disaster. The mood was sombre, of remembrance of hurt, pain and loss, rather than hope of renewal and a better future.
The levee breaks flooded 80 per cent of the city. In some neighbourhoods, it looks as though the storm hit not a year, but just a week ago. There is the same silence and abandon, the same debris. In some houses, the same furniture rots where it stood 12 months ago. Where else but in New Orleans would you find a company called Homewreckers Incorporated advertising its services on television, offering "to make this difficult task a little easier"?
Half the city's 500,000 population has moved elsewhere, an internal American diaspora unmatched since 1930s. Some returned for the anniversary, such as Morris Alexander, who before the storm was a postman with a delivery route in St Bernard Parish. "It's like a dream, but it was real," says Mr Alexander, who now lives hundreds of miles away in Ohio, of that terrible day. But he has no immediate plans to return permanently. "What it's going to take is help from the city government, otherwise I'm not coming back."
However it was the mayor, Mr Nagin, freewheeling and outspoken, for better or worse the emblem of New Orleans in its darkest hour, who best captured the challenge facing his city. This first anniversary had been a huge psychological hurdle, he said. "We must not keep wallowing in our despair. If we get through today, and most important if we can get through this hurricane season without getting hit, things will get better." Those are two very big "ifs".Reuse content