Q: the flight is from Los Angeles to Washington DC what if i'm underage?
A: Here are the accepted forms of ID per the TSA. http://www.tsa.dhs.gov/travelers/airtravel/acceptable_documents.shtm If you are underage I don't believe you need to present ID, however, having some kind of ID is recommended. It is best to call your airline and inquire with them about what you should do. If you don't have a driver's license you may want to get a state ID card. This is issued by the dept of licensing (where you go to get your driver's license).