Abu Dhabi Airport Terminal 3 launched US immigration preclearance in late January, allowing passengers on nonstop flights to the US to be processed through US immigration prior to departure. Currently Etihad serves New York, Washington and Chicago from Abu Dhabi. Upon arrival in the US, passengers deplane as if arriving from a domestic flight and can smoothly head to their connections. Abu Dhabi joins 15 preclearance locations in Canada, Bahamas, Bermuda, Aruba and Ireland.
Sometimes Preclearance works well (Dublin), sometimes not (Montreal), but irrespective it puts immigration procedures prior to the flight so that travelers can eschew huge connection buffers and missed connections dealing with immigration upon arrival. My personal rule in international travel is to always connect anywhere but the US so my US port of first arrival is my final destination.
Preclearance is distinct from Trusted Traveler Programs like Global Entry. Though Global Entry is at some preclearance locations , it is not at Abu Dhabi (see Global Entry locations).
There has been some controversy, drummed up by the anti-competitive instincts of US airlines, over the CBP’s decision to implement Preclearance at Abu Dhabi. Etihad is footing 85% of the operational cost. I do not know the legal and security intracacies of the arguments. These are US citizen CBP agents screening all passengers and it seems sensible from a security and immigration perspective to screen passengers before they show up in the US.
The WSJ reports that Qatar’s new airport, scheduled to open later in 2014, is the next to apply for preclearance.
Update: Ajay from Live from a Lounge, in the comments below notes that Dubai may be next. There have been numerous media reports about Dubai, however none that I have seen confirm that it has formally applied or if there is a specific timetable.