When is a boy's hair too short?

I'm in Texas too and most of the young AA(African American) boys in elementary school have very short hair, as do plenty of CC(Caucasian/white) boys. As long as he isn't bald/shaved, it sounds like his hair is kept extremely short. I think it is a nice clean look and certainly one is easy to maintain. As the boys get older they are able to grow it little longer because they can then deal with keeping it combed and neat.