Q. What kind of ID is required at airports for young children ages 6 and 9? I understand they need a passport for international trips, but what about IDs for domestic flights?
A. Children and minors under the age of 18 are not required to show ID for domestic travel.
Once they hit late adolescence, it's probably a good idea to bring along something, be it a birth certificate, state-issued learner's permit, or even a passport, in the event they should be grilled by a TSA agent or airline employee, but if they are under 18, no ID is required.
If your children are traveling as unaccompanied minors, the airline will require a photo ID from the adults dropping them off and picking them up.
The airline may also require proof of age for children traveling as lap children or, in some cases, a doctor's letter for newborns.