沒這回事。自己不去申請，美國不認你是公民。

How the Foreign-Born Children of American Citizens Can Prove or Obtain U.S. Nationality


Whether from an overseas consulate or the immigration authorities in the U.S., you should be able to obtain proof of your acquired or derived U.S. citizenship.



http://www.nolo.com/legal-encyclopedia/how-the-foreign-born-children-american-citizens-can-prove-obtain-us-nationality.html