Originally Posted by
bankops
Customs for flights from the US to Canada are cleared in Canada.
Customs for flights arriving in the US are cleared in the US. There is no "in transit" in the US. You arrive, you go through Immigration and Customs.
This is incorrect.
Most Canada-to-US flights undergo US preclearance at their Canadian departure point. Passengers arriving on those flights from Canada are treated as standard domestic arrivals.
As a matter of information, CBP publishes a list of Pre-Clearance ports in Canada, the Carribean, Ireland, and UAE:
https://www.cbp.gov/border-security/...s/preclearance