The stated demographic statistics don't tell the whole story, far from it. The portion of the population that fled (3/4ths seem to have fled pre-hurricane) was most likely disproportionately white and wealthier than those who remained, so the remnant population in NO when it flooded was much more black and poor than the census figures.
The weird breakdown of rich whites/high rate of college degrees vs poor blacks is a characteristic of many cities, like New York or even San Francisco for instance. These urban areas often have a pretty intense class split, compared to the suburbs, which tend to be more even.
Yes, but still the 10.7% of Masters, Professional and Doctors degrees in New Orleans versus the 8.9% National Average is a surprise to say theleast.
Detroit, e.g., has a 4.2% figure versus 10.7% for New Orleans.