Having lived in SC, I can say this:
SC has one of the highest (if not THE highest) percentage of african american citizens among its popualtion of any state. Yet it is extremely divided along race lines in almost every aspect of life, including sports. XC is a "white boy" sport to many many people you will talk to who were born and raised in the state - white or black. So, it's not surprising to see only 3 black kids in a xc state meet race. Remember, the Confederated States of America battle flag still flies at the state house. It's not up on the dome anymore, but it is being carried by a giant Confederate soldier on a horse statue which is on the grounds of the state house.
Things are changing some, but at a much slower rate than most places around.