Take the police and the army out of New Orleans and the place would be a ghost town. There is nobody left. Street after street is so empty that after a few days you get to know by sight the couple of desperate people who have remained behind.
Their logic is pretty simple. They hadn't been flooded, they had enough food and water to sit it out and they wanted to stay in their own homes. But in doing so they were defying the increasingly strident demands of the Louisiana authorities to leave and warnings that if they didn't abandon their homes they would be forced to do so.
In Johnny Whites bar in Bourbon Street this week, locals were adamant that they were not going anywhere. When I asked them what they thought of the rescue efforts in the aftermath of the storm they burst out laughing. They said they had received absolutely no outside help whatsoever.
Their feelings are reflected by people I met in the Houston Astrodome. There the scene is almost beyond belief. The stadium is a huge indoor complex, built to seat 50,000 people. The floor area, which was designed to stage football games, is completely covered with camp beds. It is now home to some 20,000 people evacuated from New Orleans and they all have a similar story to tell.
One man told me how he had spent two days on his porch waiting with his family for help. Helicopters passed overhead but no one came. Eventually he got an airbed and paddled for hours before he met someone with a boat. They made several trips to collect his family and then spent a further two days sleeping out on the Interstate Highway before buses brought them to Houston. He blamed the government rather than the storm for what had happened to him: the floods could have been avoided if the levees had been maintained, he reckoned.
Another man spent days in the New Orleans Superdome with his family. It was "just like Iraq, 'cept we didn't have the uniforms or the guns," he told me. Again he blamed the authorities for what happened, his anger even greater after they had been evacuated from the Superdome at gunpoint by the National Guard.
Almost everyone affected in this way in Houston is black and they say they didn't evacuate before Katrina because they believed it would be just another storm. And in reality it would have been, had the levees keeping the water out of the city not collapsed. Evacuees say government cutbacks under the Bush administration meant the dykes had been in disrepair for many years.
But the amazing thing about this city is that parts of it have escaped pretty unscathed. You can drive through large parts of the city and see little more than ripped roofs and downed trees. Along Canal street and Bourbon Street the pavements are littered with broken glass, brick, wood and metal, but the water kept away. But walk 100 metres up towards the city and the stinking water starts. It is in parts green, black, slimy and it stinks. It quickly goes from a depth of a few inches to one where it covers the first floor of houses.
The authorities want the city empty to try and ensure there will be no outbreak of disease or looting.
But anyone thinking of looting anything in the city this week would think again when they see the size of the military and police presence. Even getting into the city is impossible for most people. A press card does wonders in the US, but even with that it was a long and involved drive to get to the city centre. I was stopped at least ten times while driving in, the police always friendly and helpful.
Once inside there is nothing. Any food, petrol or water you think you need you will have to bring with you. If you run out, it will take a drive to Baton Rouge, two hours away, to get a refill. There are no shops, no hotels, no power, nothing. Journalists are sleeping in their cars, and even in Baton Rouge there are no hotel rooms available.
One of the huge side-effects for people in the surrounding area is a severe shortage of petrol. Many gas stations are closed and others have long lines of cars outside. The garages themselves are refusing to take credit cards: it's cash only. There have been reports of fights in queues and the National Guard have been called out to the worst affected.
However, it appears that the reports of gang warfare and of firing at helicopters have been grossly exaggerated. There was widespread looting and the signs of that are everywhere to be seen: some shops inexplicably untouched, others totally cleared out. The discarded clothes and shoes taken from shops are everywhere on the streets but it was the food shops which were totally emptied out, especially those in the vicinity of the Superdome, where people underwent the conditions of hell for days on end.
The shops and main streets will recover quickly, don't believe reports that the city is destroyed or beyond repair. The French Quarter, to where most tourists gravitate, is relatively unscathed. Whether it can regain its jazz soul is another matter, given that many of those displaced will never return. The city is probably changed forever. The clean-up will take months, even years.
Interest here is now turning to the fall-out, the blame game. Experience tells us the victims will be quickly forgotten. One can only hope people don't forget who was responsible, not only for the poor rescue efforts in the early stages of the crisis, but also for the poor condition of the levees following years of cutbacks.p
Fergal Keane is a reporter with RTÉ Radio's Five Seven Live