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.

On Thursday, the TSA began placing signage around airport security checkpoints to inform travelers of the new TSA rules going into effect in 2018.

The IDs from these nine states do not meet the federal government’s minimum security standards. And, according to the REAL ID Act of 2005, federal agencies (like the TSA) are prohibited from “accepting for certain purposes driver’s licenses and identification cards from states not meeting the Act’s minimum standards.”

In order for states to pass the government’s security standards, they must verify every ID applicant’s identity, put anti-counterfeit technology in the production of the card and conduct background checks on those who issue driver’s licenses.

If the nine states currently on the list change their ID process, the government “may grant extensions or determine compliance for additional states as warranted,” the TSA said in a statement. “TSA will update signage if and when states that are currently listed receive extensions.”

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.

Only 24 states (plus Washington, D.C.) currently comply with the rules set forward in the act. The remaining states have been given extensions (through 2017) to meet REAL ID standards.

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But the process to change state-wide ID standards is lengthy. Legislature in many of the states, including Missouri and Kentucky, has been issued to the state house floor in order to comply with federal government standards. But these bills may have trouble getting passed due to growing concerns over privacy.

Travelers from the nine states can either get a passport or wait and see if their state’s laws change in time to comply with the TSA.