AA isn't terribly larger than UA domestically, it is, but not by as much as I thought. AA's very large Carribean presence (where UA has next to none) and sizeable Latin/Central American network was a surprising factor in overall size. Last time I looked, UA was still bigger to Europe (though with DUS and MXP soon to be gone they may equal out), though DL was larger than both UA and AA. The scariest thing I saw on the particular chart I was looking at was how quickly Southwest was catching up to AA/UA/DL, especially post-9/11.