In 1804, the Supreme Court had to decide Murray v. The Charming Betsey, 6 U.S. (2 Cranch) 64, a case involving Jared Shattuck, a man who was born in Connecticut, and who moved to the Danish-controlled island of St. Thomas as an "infant" (then the legal term for anyone under 21) in 1789 or 1790. While there, he "carried on trade as a Danish subject, had married a wife and acquired real property on the island, and also taken the oath of allegiance to the Crown of Denmark in 1797."

The actual dispute was about government seizure of a vessel owned by Jared Shattuck. The seizure of the vessel was legal if Shattuck was a U.S. citizen (subject to an embargo), but was illegal if Shattuck was a Danish citizen (not subject to the embargo).

The Supreme Court seemed to take for granted that a person born in Connecticut was a citizen of the U.S. at least until he left and took an oath of allegiance to another sovereign power, but held that Shattuck had done whatever was necessary to take him outside of the protection of the U.S. government.

In the 1833 case of Inglis v. Trustees of Sailor's Snug Harbor, 28 U.S. (3 Pet.) 99, describes as "settled doctrine" that anyone born on U.S. soil who left its territory before the Declaration of Independence is not a U.S. citizen, but that anyone who remained had the right to elect whether they would remain British subjects (by leaving the United States) or citizens of their state (by remaining within the state) and ultimately citizens of the United States. There are some other wrinkles about how to prove that someone elected for one option or another, but basically moving away sometime between 1776 and the signing of the treaty where the crown recognized American independence was seen as electing to be a British, rather than an American, citizen.

Between those two cases, it seems to just assume that anyone born in the U.S. is a U.S. citizen, with a few exceptions discussed in more detail in Wong Kim Ark v. United States, 169 U.S. 649 (1898), where the Supreme Court decided that the Fourteenth Amendment guarantees birthright citizenship to anyone born on U.S. soil, except Indians born on reservations, children of foreign diplomats, and children of hostile military occupiers.