American citizens must have a passport or military identification card upon entry into the United States by air.
American citizens are required to have a passport or one of the documents listed on the Western Hemisphere Travel Initiative list to enter by land or sea.
Lawful residents that are not citizens of the United States are required to have a passport if they enter the country by air. If they enter by land or sea, a permanent resident card may be used.
Regardless of your country of origin, you must supply a passport to enter the United States by air. Land and sea requirements can differ depending on country of origin and other factors. The Department of Homeland Security provides a list of acceptable travel documents (see Resources).
Due to heightened security, travel regulations into the United States rapidly change. Check your specific travel requirements based on how you plan to travel and where you are coming from.
