When flying domestically in the USA, is it necessary to have ID for child passengers?

Question

This will be my first time flying with my 4 year old boy. I don't want any hassle at the airport. Does he need an ID of some sort? We have a birth certificate if needed.

Answer 1

I just flew Continental within the US with my 4 year old grandson with no documents, no problems (except the temper tantrum).

Answer 2

Children under 18 traveling with their parents inside the U.S. do not need I.D.  See site below to see united Airlines policy.

Answer 3

I always have my children's passports just in case (birth certs are ok too).  Also, this may not even apply to you but, if you are divorced and remarried and your child has a different last name than you do, they may ask for a birth certificate to prove that you are the child's parent.  Happy travels!