My 16-year old is considering a non-stop cross-country flight by herself. She does not have a driver's license or an unexpired passport. She does have a school ID with a picture. Will that be sufficient to get her through the TSA checkpoint? Or do we need to panic and try to get an expedited passport or official state ID? I could accompany her to the checkpoint, and I do have ID. The airline is probably United, but we could consider a different one if that would make any difference.
(TSA means this question is for the United States.)