Several states have struggled for years to comply with the REAL ID Act, a 2005 federal law that requires state driver's licenses and ID cards to have security enhancements and to be issued to people who can prove they are legally in the United States.
With a January deadline looming, lawmakers across the country have been scrambling for legislative fixes so residents can board flights and travel without confusion.
Washington state was the latest to try to bring its system in line with those requirements, as Gov. Jay Inslee signed a measure Tuesday creating a two-tiered licensing system.
Here's a look at the federal law and the potential impacts: