YSK Come 1/22/18, residents of nine states will need a passport to board any flight, domestic or international

The nine states are:

Kentucky Maine Minnesota Missouri Montana Oklahoma Pennsylvania South Carolina Washington

Each of these states does not currently issue a state ID that lives up to federal ID minimum security requirements, according to the REAL ID Act of 2005.

Green cards and military IDs will work too.

9 States Will Require Passports for Domestic Flights Within the U.S.