From the TSA website:
>>>>Proper Identification
If you have a paper ticket for a domestic flight, passengers age 18 and over must present one form of photo identification issued by a local state or federal government agency (e.g.: passport/drivers license/military ID), or two forms of non-photo identification, one of which must have been issued by a state or federal agency (e.g.: U.S. social security card). For an international flight, you will need to present a valid passport, visa, or any other required documentation. Passengers without proper ID may be denied boarding.
For e-tickets, you will need to show your photo identification and e-ticket receipt to receive your boarding pass.
There are four ways to obtain a boarding pass:
Go to your airline's ticket counter at the airport
Use curbside check-in
Use your airline's self-service ticket kiosk in the airport lobby
Print the boarding pass from your airline's website
Note: Persons with parental, official, medical business or similar reasons may be able to access the checkpoint, but should check with their airline for required documentation.<<<<<