[ubernostrum]

US preclearance exists in certain airports in Canada, Ireland, Bermuda, the Bahamas, Aruba, and the UAE.

The US-Canada agreement is the oldest one, largely due to the amount of cross-border air travel, and Canada has the right under the agreement to operate preclearance stations for the Canadian border inside US airports, but has never chosen to do so.

[taway_1212]

I've learned that, when coming to the US from Europe, if I can't get a direct flight, I prefer my change to be in Canada. This way, I can pass immigration on the Canadian airport, while I'm idling between flights anyway. Also, the one time I did it, there was almost no queue (in Toronto).

[kalleboo]

When I had a connection in Canada, my incoming flight was delayed, the lines were long and I was at risk of missing my connection, so I made the opposite conclusion.