All U.S. citizens and nonimmigrant aliens from Canada, Bermuda, and Mexico departing from or entering the United States from within the Western Hemisphere at air ports of entry are required to present a valid passport, NEXUS card (if utilizing a NEXUS kiosk when departing from a designated Canadian airport), Merchant Mariner Document (for U.S. citizens traveling on official business), or Military Identification Card (for members of the U.S. armed forces traveling on official orders). Note that children are also required to present their own passport when traveling by air.
Requirements for lawful permanent residents of the United States are not changed by the implementation of WHTI. Lawful permanent residents must continue to present a valid Permanent Resident Card. A passport is not required.