what can be used as proof of identity
Identity document Since February 1, 2008, U.S. citizens may apply for passport cards, in addition to the usual passport books. Although their main purpose is for land and sea travel within North America, the passport card may also be accepted by federal authorities (such as for domestic air travel or entering federal buildings), which may make it an attractive option for people residing where state driver's licenses and I.D. cards are not REAL ID-compliant, should those requirements go into effect. TSA regulations list the passport card as an acceptable identity document at airport security checkpoints.[97]
National identity cards in the European Economic Area National identity cards are issued to their citizens by the governments of all European Union member states except Denmark, Ireland (Public Services Card) and the United Kingdom, and also by Liechtenstein and Switzerland (the latter not formally part of the EEA). Citizens holding a national identity card, which states EEA or Swiss citizenship, can not only use it as an identity document within their home country, but also as a travel document to exercise the right of free movement in the EEA and Switzerland.[1] Identity cards that do not state EEA or Swiss citizenship, including national identity cards issued to residents who are not citizens, are not valid as a travel document within the EEA and Switzerland.