the US is a bit tricky on this, while i dont think the nation as a whole requires ID, but most if not all of the states require persons over 18, 16 in some, to carry a valid state issued or military ID card. they can actually fine you for not having it. a drivers license covers the state issed ID as the 2 or hardly different besides the words at the top, hell you have to get the ID at the department of motor vehichles anyway lol