Like it or not, it was the 14th Amendment that made that possible.
Here is the short reference, but I'll go into detail for those wanting to understand the truth.
a. Section 1993 (48 Stat. 797) was amended by the Act of May 24, 1934, to permit American women to transmit U.S. citizenship to their children born abroad, regardless of the father’s citizenship.
b. The amended Section 1993 was in effect from May 24, 1934, at noon Eastern Standard Time until January 12, 1941. The text of the amended law is shown in 7 FAM 1135.6-1. It was repealed, and superseded by the Nationality Act of
In 1868 the Fourteenth Amendment as follows...
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.
Article I, section 8, clause 4 of the United States Constitution expressly gives the United States Congress the power to establish a uniform rule of naturalization.
Only natural born citizens are eligible to serve as President of the United States or as Vice President. Though the text of the Constitution does not define the meaning of natural born, in particular it does not specify any distinction to be made between people whose citizenship is based on jus sanguinis [parentage] or those whose citizenship was based on jus soli [place of birth]