Source: http://uslex.com/Naturalization-and-Citizenship.html
Timestamp: 2019-04-22 20:26:20+00:00

Document:
The Immigration and Nationality Act grants U.S. citizenship at birth based on: (1) birth in the U.S. [INA §§301(a)-(b) and (f)] or certain other places [INA §§302, 304-07]; (2) the citizenship of one or both parents [INA §§301(c)-(d), and (g)-(h)]; and (3) a combination of location and parental citizenship [INA §§301(e) and 303]. U.S. citizenship is also granted to persons after their birth based on a combination of parental citizenship and later residence [INA §§320 and 322] and by naturalization [INA §316]. U.S. noncitizen national status is granted based on the birth location in certain other places [INA §§308(1) and (3)], and the U.S. national status of one or both parents [INA §308(2) and (4)].
A. Birth in the U.S. or Certain Incorporated Territories-Under the Fourteenth Amendment "all persons born or naturalized in the United States...are citizens of the United States."
B. By Acquisition at Birth. Generally-A child born outside the U.S. where one or both parents are USCs may acquire U.S. citizenship at birth. INA §301(c)-(e), (g)-(h), 8 U.S.C. §1401(c)-(e), (g)-(h). Acquisition of citizenship for a child born out-of-wedlock is also provided for under INA §309, 8 U.S.C. §1409. The latter provision requires the mother to be physically present in the U.S. for only one year to transmit citizenship. INA §309(c). A child who acquires citizenship is a citizen at the moment of birth and does not need a certificate of citizenship. See U.S. v. Smith-Baltiher, 424 F.3d 913, 920-21 (9th Cir. 2005).
C. By Derivation Through the Naturalization or U.S. Birth of One Parent-A child born outside the U.S. may become a USC as a matter of law by virtue of his or her parent or parents' birth or naturalization. INA §320, 8 U.S.C. §1431; 8 C.F.R. §320, 66 FR 32138, 32166 (June 13, 2001).
D. By Naturalization-A person who is 18 years or older, who meets certain requirements, including residence, presence, good moral character, and legal status, may file an application for naturalization. INA §316, 8 U.S.C. §1427.

References: §316
 §308
 §301
 §1401
 §309
 §1409
 §309
 v. 
 §320
 §1431
 §320
 §316
 §1427