Once inside a US pre-clearance area, you are essentially treated as if you are physically inside the USA already. Once, at YYC
, I was on a trip to the SFO
. I was already through US pre-clearance and at my gate. Then, I was bumped from the direct flight to SFO
, and booked onto a new itinerary, YYC
. I had to leave the US pre-clearance area and head to a domestic gate for the flight to YVR
. I had to go through Canadian customs and immigration in order to leave the US pre-clearance area.
As such, when you arrive in the US, you arrive like a domestic. You get off the plane, and go collect your luggage, or if you have a connecting flight, your luggage will be transferred, and you just need to walk to your gate. No talking to any CBP
I expect that passengers using US pre-clearance, in any airport where it exists, would be treated like this. I expect that if you entered the the US pre-clearance in DUB
, you would either have to fly out, or you would have to go through Irish customs, in order to leave the pre-clearance area.