Citizens from the United States are not expected to carry a passport, but they must display a valid form of identification issued by a federal or state organization. This can include U.S. military identification, a permanent resident card, a border-crossing card, a driver's license, an American Indian tribal photo identification or a transport worker identification credential. All forms of identification must display the name, date of birth and gender of the passenger, as well as the expiration date and tamper-proof feature.
According to the Transportation Security Administration, non-U.S. or Canadian citizens do not need to carry passports if they have documents issued by the U.S. government, such as a permanent resident card. Those who do not should carry their passports.
It is always best to check with the airline prior to flying if you are unsure of the correct identification required. Those who do not carry an approved form of identification may be subject to additional security checks and may not be permitted to fly.
