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 identification number A national identification number, national identity number, or national insurance number is used by the governments of many countries as a means of tracking their citizens, permanent residents, and temporary residents for the purposes of work, taxation, government benefits, health care, and other governmentally-related functions. The number appears on identity documents issued by several of the countries.