Originally Posted by
84fiero
Which is understandable, given that the 14th Amendment confers citizenship automatically upon anyone (with very few exceptions upheld by the Supreme Court such as foreign diplomats or hostile forces) born on US soil, regardless of the citizenship of their parents.
Of course that doesn't mean that people born here never renounce US citizenship.
That's exactly the issue. The overwhelming majority of people with a U.S. birthplace are citizens, due to the US use of juris soli in the form of the 14th Amendment. The U.S., like most countries, also requires its citizens to use their US passports on entering the country, even if they have one or more other valid passports. Therefore an arriving passenger bearing a foreign passport specifying a US birth place would appropriately raise some questions in the immigration officer's mind. However, U.S. citizen born outside the USA who presented themselves at a port of entry with a foreign passport would not ordinarily raise such concerns.