It might soon become mandatory to use a passport as identification at the airport even when the travel is domestic within the U.S. By January 22, 2018 the Department of Homeland Security wants all the states to comply with the REAL ID Act.
The REAL ID Act was created 12 years ago and half the U.S. states are following the act’s regulations. Getting the rest of the states there is a bit more complicated.
California, Oregon, Washington, Alaska, Pennsylvania, Virginia, and South Carolina have already been given an extension through October 18, 2018.
Other locations are currently under review for their extensions but it is unclear whether they will receive them or not. Those places include New York, Michigan, Illinois, and Louisiana, Puerto Rico, Guam, and the U.S. Virgin Islands.