“The distinction between citizenship by birth and citizenship by naturalization is clearly marked in the provisions of the Constitution, by which
“No person, except a natural born citizen or a citizen of the United States at the time of the adoption of this Constitution shall be eligible to the office of President,”
and “The Congress shall have power to establish an uniform rule of naturalization.” Constitution, Article II, Section 1; Article I, Section 8. By the Thirteenth Amendment of the Constitution, slavery was prohibited. The main object of the opening sentence of the Fourteenth Amendment was to settle the question, upon which there had been a difference of opinion throughout the country and in this Court, as to the citizenship of free negroes (60 U.S. 73; Strauder v. West Virginia, 100 U.S. 303, 306.
This section contemplates two sources of citizenship, and two sources only: birth and naturalization. The persons declared to be citizens are “all persons born or naturalized in the United States, and subject to the jurisdiction thereof.” The evident meaning of these last words is not merely subject in some respect or degree to the jurisdiction of the United States, but completely subject to their political jurisdiction and owing them direct and immediate allegiance. And the words relate to the time of birth in the one case, as they do to the time of naturalization in the other. Persons not thus subject to the jurisdiction of the United States at the time of birth cannot become so afterwards except by being naturalized, either individually, as by proceedings under the naturalization acts, or collectively, as by the force of a treaty by which foreign territory is acquired.”
Elk v. Wilkins, 112 U.S. 94 (1884)
If someone doesn’t require naturalization, then they were born a US citizen. And there are only two ways to become a US citizen - birth, or naturalization.
Also feel free to read Wong Kim Ark, and its lengthy discussion of the meaning of natural born subject/citizen.
http://www.law.cornell.edu/supct/html/historics/USSC_CR_0169_0649_ZO.html
Sorry, but there needs to be better precision than that. And yes, I will do the reading. In your sentence I copy above, I see that you left out the words "natural born." I think 95% of us are in violent agreement that a child born on US soil is a US Citizen. But that is NOT the question.