On American, we've needed ids for our 16 year old DD on all three trips we've taken to WDW since 9/11. On the first trip, we had to show ids three times...security, gate and as we boarded. That was in early October. Since then, each leg has varied. Coming home in March, my DH and I had to show ours as we checked our baggage but only had to show our kids' as we boarded. If your child doesn't have a school id (ours didn't until high school) or passport, perhaps your DMV will provide one. In Illinois, I understand that you can get one that way, although we have never done so.