My mother and I are meeting in Denver to depart for a trip to London on Icelandair. To get to Denver, we each booked unconnecting flights from our respective cities. These flights are on Delta and Frontier, from Detroit and Spokane.
My question is: when we get to the airports for these US flights, do we show our passports and say that our final destination is in London? Or do we just act like we are flying to Denver on a domestic flight and then do the whole international thing when we check in at the Denver airport for our international part of the trip?