What kind of proof does my infant need to crossborder?

Question

Mother is USA and Father is Canadian

Baby will born in Canada but wants to visit USA for 2 wks vacation by land (DRIVING) so what kind of proof do we need to show at the border for the baby?

Answer 1

You just need the birth certificate.  

If only one parent is traveling with the child, it would be a good idea to get a notarized permission letter from the other parent.