I've done the border crossing on my way to and from Montreal via car, bus, train and plane and all post 2001. As is expected, car was by far the easiest. To be honest, my experiences flying have been some of the worst. At least when the train gets inspected I can relax in my seat and continue reading, using my computer, etc. Try standing for an almost equal amount of time at YUL upon arrival (doesn't seem to happen when returning to the US). I can't explain it. Maybe its just bad timing on my part. Anyways, I digress.

Back on topic and to your question, yes, I have seen Greyhound strand someone. The gentleman sitting next to me from Montreal to New York had some paper issue and they loaded everyone else back on the bus and continued on to NYC.


Cheers.