There’s been a lot of debate lately about the citizenship of presidential candidates and the constitutional requirement that only a “natural born Citizen” is eligible for the Office of President. You can find the relevant provision in Article II, Section 1, Clause 5 of the United States Constitution.
It was not until 1868, however, that the Fourteenth Amendment established “birthright” citizenship, declaring all persons born in the U.S. to be citizens. That was only one aspect of the amendment’s profound importance. For a brief introduction to what historians and scholars describe as the most important amendment since the adoption of the Bill of Rights in 1791, see this excerpt from Professor Michael Roffer’s recently published The Law Book: From Hammurabi to the International Criminal Court, 250 Milestones in the History of Law.