Originally Posted by
manually
Canada really is not international for air travel purposes. You usually clear customs in both directions on the Canadian side. I had short tight connection flights via SEA, but usually the gates were close so no issues. Finally, Delta schedules extra time for flights usually you come in early.
What? It very much is international. Same laws and security rules apply for Canada as for UK. Positive bag matching happens, etc... On return you even must show your passport or Nexus card at gate. This despite already clearing US CBP before getting to the gate.