Originally Posted by emcampbe

wait, you got asked for your passport before boarding, CHS-IAD and IAD-SFO on segments in your YVR itinerary? Canada does require a passport check at boarding for segments to/from Canada, and it should definitely be checked at check in, either by a kiosk if using that, an agent if checking in with them, or on the app (first time using a given passport, you need to take a photo, if not, you can select one on file). But in 10+ years of flying UA transborder, almost always with a connection on UA, I've never been asked for a passport at gate/boarding except for the specific segment to/from Canada.