Newbie question, but I just want to clear this off my mind. I'm flying from ICN to JFK, in two weeks, with a layover in YVR, both flights on Air Canada. Do I need to go through customs at YVR and/or at JFK?

If I do go through customs at YVR, will two hours be enough? So, I hop of the plane grab my luggage, go through customs, and then I recheck in right? Sorry, it's my first time doing a layover in Canada into the states, so I'm not sure and I've heard YVR customs horror stories.

I'm a US citizen if that's any help. Thanks for any help!