I'm not sure if everyone is aware or not, but you can send a birth announcement to the White House and the baby will get a letter back. Not terribly exciting, but nice to put in the baby book. I did it for DD1 and got one back pretty quickly.
https://pregnant.thebump.com/new-mom-new-dad/newborn-basics/qa/letter-to-baby-from-president.aspx
Re: Letter from White House to baby
I just sent one of her birth announcements. I can't remember if I included anything else, so I think this time I will add our address on an index card just in case they don't get it from the envelope.