Originally Posted by
Often1
While AA will tag the bags LGA-HNL, OP still has to claim them, carry them through US Customs and drop them at YUL. The check-through will save a minute or two in line, but he still faces US pre-clearance and an additional round of security at YUL.
Actually, OP might have to clear Canadian customs, grab bags, drop bags, and then clear US customs during his layover. Not sure if exactly how the transit will work since he is coming from the US but still needs to clear US customs for preclearance.