Hmmm... that is an interesting topic. I thought that ORD might be close, with UA having a few of them, but another one that no one has mentioned is DFW. Does AA fly many of them there? What about DL? ATL should have quite a few, I also see tons of them. If someone actually takes the time to figure this out, it would be interesting to see. Where are UPS's hubs, I know they have a good number in their fleet.
A woman drove me to drink and I didn't have the decency to thank her. - W.C. Fields