When he was born, the hospital would have had his mom fill out a form for the office of (or bureau of)
Vital Statistics for his location (this is usually a state office). Either the hospital or the mom would have sent it in, and the state would have put the information into its database and sent her his official birth certificate. If she decided to change his name later, if she did it by legal actionl, the bureau of Vital Statistics would have that information also.