Beginning Jan. 22, 2018, travelers from nine states will no longer be able to travel with only their driver's licenses. Residents of Kentucky, Maine, Minnesota, Missouri, Montana, Oklahoma, Pennsylvania, South Carolina and Washington will have to use alternate ID forms (passport, military ID, or permanent resident card) to pass TSA security checkpoints -- even for domestic travel. The IDs from these nine states do not meet the federal government's minimum security standards.
Travelers who are not from the nine states will not be affected by the change in 2018. But by 2020, all travelers must have identification in compliance with REAL ID or they will not be allowed through TSA security checkpoints.