URGENT! What are the travel ID requirements for children while flying w/in the US

URGENT! What are the travel ID requirements for children while flying w/in the US?
We are moving back to the mainland, while packing & shipping, we packed away our 3year old's birth certificate & SS card. (This was purely unintentional) We have never needed them before while flying. I'm concerned because one of our flights is the second leg of an international flight. (Honolulu > mainland) This will be our second flight so we will have already been thru security on Maui. With only 6 days until our move, I'm at a loss of what to do. As I said, we've never needed or been asked for them previously, but we have never boarded an international flight like this either. I'm sick to my stomach with worry. Has anyone had their childs ID checked while flying?
Parenting - 3 Answers
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1 :
children need an adult and a plane ticket. thats all
2 :
Children don't need anything.
3 :
Usually they just need a ticket and a mommy. Do you have an old birth announcement or anything, just in case? Or a family photo that's fairly recent? Your fear is probably that they won't he's yours. If you have photos of you and him, that should erase the doubt.