Originally Posted by MapleLeaf
As the flight will pass over U.S. territory, then the 2 countries share advance passenger information. Since you are originating from Canada, they will ask for your passport before you board... really, really doubt they will take just a DL.
Well, I have flown to Mexico before without a passport. For American citizens, you don't need a passport. Just like you don't need a passport to go to Canada. So why would it make a difference if I fly from Canada directly to Mexico with a DL only? And what do you mean they share information? You mean the airline shares info with immigration?