To get through airport security in Toronto for a flight to the United States, you now have to go through eight different screening lines or ID checks. Most passengers either get a pat-down or have their carry-on bags unpacked on tables, with every toiletry kit and pajama pair carefully checked.

And tight restrictions on carry-on luggage force most road warriors to check their roll-a-board bags. "Ever since the underwear bomber thing, it's been ridiculous," said Kevin Koski, who was headed home to Miami from a job interview...