Boarding Pass
All airports require that passengers have their airline boarding pass to enter an airport terminal. The ticket must be ready to be presented to airport security.
Photo I.D.
A photo identification, like a state-issued driver's license, must also be presented to airport security at the terminal gate. The I.D. and boarding pass are both needed for any United States air travel.
Passport
A nationally issued passport is required for entry into the United States by air. United States citizens, even children, must present a U.S. issued passport.
Military I.D.
Military identification can be substituted for a passport when presented with travel orders from the service member's military branch. This can also include a Coast Guard-issued Merchant Mariner Document (formerly known as the Z-card).
NEXUS Card
A NEXUS card can be used in place of a passport for U.S. citizens. This card is issued by the NEXUS program, a joint venture between the American and Canadian customs agencies,