Do children under the age of 2 need Identification to travel?

If you are going abroad then normally young kids need their own passport (or some countries allow young kids up to a certain age to be included by name on their parents passport) but for US citizens even infants need their own passports. If you travel domestically I would take a copy of the child's birth certificate for proof of age as some airlines may require it. You can check with your airline beforehand if you want.