If you’re one of the 9.5 million of Americans living the Louisiana, Minnesota, New Hampshire and New York, you may have to start using a passport to fly, even domestically.

Those four states have refused to comply with stricter standards for state-issued IDs the U.S. government issued about a decade ago. But, with the looming deadline for the Real ID Act to go into effect, the TSA will demand that those residents use passports rather than drivers licenses to board flights.

The TSA will accept $55 passport cards and $135 passport books as valid identification.

Minnesota was just denied an extension. The other states were granted temporary waivers, and they’re in the process of making new cards and issuing them to the public.

Some states initially refused to comply because of fear that the federal government would use the new IDs to make a national database of citizens, potentially using that information to spy on the public. Others cited a high administrative cost and 50 percent increase in a fee for drivers.

The stricter standards are already being enforced in other places than airports. Recently, people with New Hampshire driver’s licenses have been turned away from federal buildings in Washington, officials said.

The failure to states to comply with the act could be disastrous for unsuspecting passengers boarding flights and cruise ships, with the potential for travelers to arrive at the airport only to miss an important flight because their state failed to provide them with proper identification.

The Real ID Act was a post-Sept. 11 measure that tightened access to federal facilities and created a national standard for state-issued IDs. The law has been rolled out by the Department of Homeland Security in several phases and could take effect in air travel some time in 2016.

What to Do if You Live In One of These States:

People in Minnesota should get passports by January if they want to fly domestically.

New York has been granted a waiver, so any form of driver’s licenses can continue to be used.

A waiver for Louisiana has been granted until Oct. 10, 2016. Existing licenses can be used until then. (The state tried to pass a law to comply with the federal mandate, but Gov. Bobby Jinal vetoed it).

New Hampshire received a waiver lasting until June 1, 2016.