Unfortunately this IS the case. On the strip, Bourbon street is pretty safe and cosmopolitan simply because that's the way the quarter is. Just be very very careful when you start walking 2-3 blocks off the main drag. Things get a LOT darker. Less traffic lights and less traffic, less people which means less witnesses. It's a very dangerous place to be, regardless of your color, but particularly if you're white. You're obviously out of place then and as such, a target.

As far as the mayor being black, consider that New Orleans proper is more than 50% black. It makes sense that the mayor would also be black.

Another interesting thing to note is that in New Orleans, over 50% of the males of working age are unemployeed. This is what leads to much of the crime problems downtown. This is also why I don't live and work in New Orleans proper. I live and work in the burbs, and very very rarely go into the city. And then, never for fun, it's all work. When I first moved here, I both lived and worked in the city. Never again.