Originally Posted by
UnitedAirlinesSuck
When she arrived at the airport the tagged her bags, and proceeded to let her through the check in line. At the very last check in they asked her what tied her to Canada. She replied family and home. Then she was refused service as "She had no real ties to Canada, and there was no proof she wasn't going to the U.S. to be a illegal citizen."
Sounds like USCIS/immigration here. Well, she probably couldn't show the officer proof that she will be returning to her home country.
It is your/your gf's responsibility that she has complete travel documents prior to crossing the border.