<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by I'llMissCP:
From my experiences, entering the US at your origin is much easier than transiting at YYZ.
You are invariably delayed there. Now you will also be charged an additional AIF in each direction.</font>
I've found that I am delayed longer and more often returning to Canada than leaving. Canadian customs usually takes longer than the US.
Although it really depends on the time of day and whether you arrive in the middle of one of the incoming plane shifts. At certain periods of the day, there are mostly landings or mostly takeoffs. I ran this regular route from YVR to ATL via YYZ for a while -- same day same flights. A difference of 15 minutes in the flight time from YVR to YYZ meant a difference of up to an hour in line. If the plane lands a few minutes earlier, I walk right to the front of the customs line and I'm through in 2 minutes.