They have a couple of really famous places like that in Texas. Another one is called the Salt Lick just outside Austin I think. I have never been there, but my brother in law went and he said it was amazing. It's not uncommon for BBQ places to have lines like that. Many times they are working with a limited supply of food and when it is gone they close up for the day. Even if it is only 2:00 PM. It's a bit more difficult to find good BBQ in the north of the US, but it does exist.