It's absurd to focus on a few backwards communities and to try to paint an entire region thusly. If we are going to do that, let's take into account Quaker community practices, and California cults, and start judging every region by the small, strange communities which are present in every state.
The simple truth is, there are endless numbers of schools in the US south holding proms every year and they are just like schools elsewhere.
If one looked I'm sure you can find schools in the north which are run by white separatists, as well as others which separate themselves from other races. Has Louis Farrakhan involved himself in any schools? How about the scientologists?
Lets stop trying to paint half the nation as sheet wearing racists.
In response to "what would Obama do about it" the answer is nothing, nothing at all. Because its a non-issue. If one is truly concerned with racism, one will find more racists in an average "Acorn" office than you will at most school prom planning committees, north or south.