Originally Posted by Indelaware

There is little reason for people ex-ORD to connect at IAD. Sure there are some smaller cities one cannot get to nonstop from ORD, but that's minimal. Therefore, the majority of the traffic between CHI and WAS on UA is O/D at WAS. Excepting for those along the new growth areas along the Dulles parkway, most people flying in/out of WAS want DCA over IAD.

Additionally, because of route restrictions at DCA, a larger number of ex-DCA passengers must connect on their way west. ORD is the place to do that.