Well, that's it. I've been flying or connecting through Dublin usually. (There have been USA formalities there also for years and years.) If it'd been some other place it Europe or Asia, it may have been different.

Boy, I'd sure rather get relocated by the CBP to Mexico City or Acapulco or Cancun or Puerto Vallarta or Guadalajara than Winnipeg or Calgary or Newfoundland. Maybe that's just me. And the margaritas on the beach. And the sunshine and the music and ... and ...

All good and accurate information so far. Since I travel in and out of YYZ frequently, I'll add my 3 cents.

Going in thru Canadian Customs I've learned to always check "business". I do have legit reasons for being up there frequently for work as we have a regional office there, but even on trips to see friends it results in a faster conversation. I give them my declaration card, boarding pass, business card and passport to expedite the process. The agents are fairly humorless, but they are far better at YYZ then they are at the Niagara Falls border.

Leaving from YYZ thru US Customs is pretty straight-forward. Again, any discussion of "reason" is limited to strictly business. The US agents there tend to be decent folks. Even had one share his I-phone backstage photos at a recent KISS concert. I much prefer clearing in Canada so I can just walk off the plane in the US.

If you are in Canada on business and you don't check that on your custom/entry form then be prepare to give quick correct answer to a bunch of quick question to verify your non-business trip.

Secondary for American on business is relatively quick unless there is a long lineup of passengers with headgear.

Dublin Departure to US - YUCK!
 

Wonderful trip to Ireland spoiled by a crummy Dublin Airport experience on 5/12. Dublin uses U.S. pre-clearence for US bound flights.

1 - Whole process took 90 minutes with SEVEN checks of my passport, yes thats right SEVEN people had to inspect my passport.
2 - Two complete security/xray checks of bags, with one saying we were on US soil (after customs) so they were the "TSA check". Irish nationals did this TSA check.
3 - The EU customs line had less than 10 people in it while the US line had more than 100!
4 - Area past security #2 (US soil?) had crummy services and shopping and the comfort of the area just sucked and was uncomfortable with no lounge access.

Overall, a very lousey way to end an otherwise wonderful trip to Ireland.

What the connection with YYZ customs here.:rolleyes: