The U.S Passport Card is a limited travel document issued by the United States federal
government in the size of a credit card. It may often be used as an identity card for
purposes other than international travel, such as domestic air travel. Like a
U.S. passport book, the U.S passport card is only issued to U.S. citizens and U.S. nationals
exclusively by the U.S. Department of State and is compliant to the standards for identity
documents set by the REAL ID Act and can be used as proof of U.S. citizenship.