Portland International Airport (PDX) recommends a testing service provided by Carbon Health for rapid COVID-19 testing ahead of an international flight. Carbon Health currently operates testing locations downtown and at the airport, and they guarantee results within 3 hours or by 2 p.m. the next day. The pharmacy chains Rite Aid and Walgreens also offer COVID-19 testing services. You will need to do your own research to ensure that both the type and timing of your test match the requirements of your destination.