Residents of states which haven't meet the requirements of the 2005 Real ID Act may be required to show a passport to fly to another state. Presently there is a grace period but that will end on January 22, 2018.
After the deadline, state issued driver's licenses will no longer suffice. Additional identification will include passports, green cards, border crossing cards, military IDs or other TSA approved forms of identification.
Source: dailymail.co.uk