What specific documents are needed to travel within the U.S.?
You only need your drivers license, you don’t need your social security card or any other form of ID. Any valid form of ID can be used instead of your drivers license like a passport, military ID, or government ID card. If you travel by car to Canada or Mexico this is also the case, however by boat or plane you need a passport. You also need a passport to travel anywhere else out of the country. You can’t even board the plane or boat without one. You should go ahead an apply for your passport now anyway. It takes forever to get one (currently 12-15 weeks) and in a year or two you will need one to travel by plane inside the USA anyway. They are good for 10 years, so you won’t have to worry about it for quite some time again.