Update...Routes where US Airways and American overlap include CLT-DFW , MIA, ORD, and LGA; and DFW-PHX, PHL, and ORD.

These and some flights from DCA could be on a list that the Justice Department would require the airlines to divest. What gets divested is usually the subject of behind-the-scenes negotiations.

Potential bidders for those slots include smaller airlines such as JetBlue Airways or Spirit Airlines, analysts say.