Originally Posted by
Kacee
No it wouldn't. You would have to clear Canadian customs and then clear US passport control in the Canadian airport. This is typically worse than coming through a US port of entry.
I'm transiting SYD-YVR back to SEA in Sep. AC rep confirmed I would not clear Canadian customs, but transit to US preclearance. AC and YVR websites confirm that routing. And there is a lounge on the US side in YVR!