The Transportation Safety Administration will begin enforcing REAL ID requirements at airport checkpoints this month, meaning that residents in Kentucky, Maine, Minnesota, Missouri, Montana, Oklahoma, Pennsylvania, South Carolina, and Washington will need an alternate ID, such as a passport, to pass through security checkpoints.

“The REAL ID Act establishes minimum security standards for license issuance and production and prohibits Federal agencies from accepting for certain purposes driver’s licenses and identification cards from states not meeting the Act’s minimum standards,” states the Department of Homeland Security.

The act was passed in 2005 in response to the 9/11 attacks in order to create more secure licenses by requiring all states to meet federal identification standards. According to the Washington Post states “need to meet tougher security standards related to card issuance, card design and application processing.”

Those nine state’s mentioned previously have not met the minimum requirements of the act and unless they applied for an extension (which all of them have), those residents will not be able to enter airports with just a driver’s license.