U.S. Presidents & The Natural-born-citizen Clause

[Wyrd of Gawd]

For the record, Martin Van Buren (#8) was the first president of the United States who was not born a British subject.... FWIW.

(Perhaps that is why they did not bother to define the term?)

Technically all white people in the country became official citizens of the United States in 1781 when they adopted the Articles of Confederation and Perpetual Union.  So Van Buren could have been from Russia and he would have became an American in 1781 if he had wanted to and there wouldn't have been any bar to him becoming President.