When flying into the USA, join the 'non-US nationals' queue nearest to the 'US nationals' sections. Foreigners are often invited to join 'locals' lines when the queues of US nationals have passed.
On the way back home, you'll find not just one check-in queue but two at US airports - and the whole process can take hours.
After passports and tickets have been checked in the usual fashion, passengers then form another orderly, snaking line to have their luggage screened – and their socks, shoes and body checked with the US 'patdown' search.
However, many airlines open their check-ins up to 12 hours ahead of the flight, which means you can arrive early, beat the queues, then go off for one last long lunch, afternoon on the beach or shop, and return to the airport a mere hour ahead of the flight.