For the past couple of years WN flew from IAD only to DEN and PHX (1-2 times a day). The last time I flew them on the IAD-PHX route the plane was half full and it was less than $200 RT. No wonder they are pulling out of IAD altogether; the routings made little sense to begin with, and they were competing directly with UA that has more frequent service on these routes as well as many IAD connections. For WN it was IAD O/D traffic only.