[Al_Capone_Junior]

Passport is acceptable.

USA driver's licence is acceptable. They very well might scan it using this new fangled computer thingie, so having a fake one might get you in considerable hot water.

If it ain't one of those two things, they'll probably be sending you to security for clearance. They can clear other types of ID, but you'd be better off just bringing one of the above two things. A military ID might be OK, but why the heck would you be 21, in the military, and NOT have a driver's licence or passport?

al