2. Aliens by election are all such natural born, or naturalized subjects of the crown of Great-Britain, as were born, or naturalized before the fourth day of July, 1776, and have not since become actual citizens of the United States;
[snip]
Aliens by election may then be shortly described to be those subjects of the crown of Great-Britain on the fourth day of July, 1776, who have elected to remain such, and have not since become, and continued to be, citizens of the United States, or some one of them.
St. George Tucker, (Annotated) Blackstone's Commentaries
This legislation from 1779 confirms Tuckers words that people remain aliens unless they formally become citizens.
Be it enacted by the General Assembly, that all white persons born within the territory of this commonwealth and all who have resided therein two years next before the passing of this act, and all who shall hereafter migrate into the same; and shall before any court of record give satisfactory proof by their own oath or affirmation, that they intend to reside therein, and moreover shall give assurance of fidelity to the commonwealth; and all infants wheresoever born, whose father, if living, or otherwise, whose mother was, a citizen at the time of their birth, or who migrate hither, their father, if living, or otherwise their mother becoming a citizen, or who migrate hither without father or mother, shall be deemed citizens of this commonwealth, until they relinquish that character in manner as herein after expressed: And all others not being citizens of any the United States of America, shall be deemed aliens. The clerk of the court shall enter such oath of record, and give the person taking the same a certificate thereof, for which he shall receive the fee of one dollar.
Thomas Jefferson , A Bill Declaring Who Shall Be Deemed Citizens of This Commonwealth, May 1779
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It would be ridiculous to think the Founders would have had everyone go to all the trouble of traveling to the courthouse, take an Oath of Allegiance, swear fealty to the Commonwealth and pay a dollar (no small sum then) if all government required to acknowledge someone as a citizen was their presence.
That pretty much blows CpnKook's theory that George Washington was a "natural born citizen" of the United States when he was born a natural born subject of King George III. And from one of his own claimed sources too!
Still, this is not the information that I seem to recall, but it has been many months since I have devoted much time or research to this subject. I may be getting something crossed in my recollection regarding who posted it and to whom it was in reference. I thought it was you, but if it was not, perhaps i'll be able to remember eventually.
This is one of the problems with reading so much information on the topic. It all starts to blur together, especially if you don't keep it refreshed.