Well, the first thing you have to understand is that Chapel Hill, being the site of a major public university and a pretty important place in its own right, is about the most culturally diverse city in North Carolina.
So once upon a time the good folks of Chapel Hill were planning on building a zoo -- for the sort of reasons that cities usually build zoos, mind you. Now, in order to build a zoo, a city has to allocate a fairly decent sum of money to the whole zoo-building process, and that sort of money tends to come through the government. So of course North Carolina's honorable Senator Jesse Helms became involved in the the collective efforts.
Of course, Senator Helms is not known for being racially tolerant. He suggested that, in order to simplify the entire zoo-building endeavor, the good people of Chapel Hill should perhaps just "build a fence around Chapel Hill." As usual, his opinion was warmly recieved by the liberal community.