Us immigration in departure lounge in shannon airport?!?

Question

i asked a question previosly about something and some1 metioned us immigration in shannon.has any1 ever used it before and if so how does it work?if i do whatever it is i have to do at immigration in shannon does that mean i dont have to do anything when i get to jfk?do i just walk through immigration in jfk if i hav already done it in ireland?i am very confused,if anyone knows how it works or has done it before could you please help me out?!thanks

Answer 1

I've done it at Shannon on  flight bound to Newark, but it was 2 summers ago.  If I recall, it was just like clearing customs and border control up arrival, except you just do it before boarding the flight.  So, when you get off the flight, it's as if you've arrived on a normal domestic flight -- just fetch your baggage where the arrivals info tells you to.