Use At Airports
A NEXUS card is the only acceptable alternative to a passport for traveling between the United States and Canada via air (citizens of other countries must still hold a valid passport in addition to their NEXUS card). Passengers entering or leaving Canada via participating international airports utilize a kiosk to report to immigration authorities (CBSA or CBP) while an iris scan is used to verify identity. Members must fill out a customs declaration card for the country they are entering and are subject to additional questioning by border personnel as well as secondary or random screenings.
NEXUS allows travelers flying from many Canadian airports, even on domestic flights, to bypass the regular security screening line and use an expedited trusted traveler line.
Read more about this topic: NEXUS (frequent Traveler Program)