> U.S. law also states that a child born outside of the U.S to a U.S. citizen parent who previously spent sufficient time in the U.S. is a U.S. citizen at birth, regardless of whether the child also has the citizenship of the country of birth or another citizenship. U.S. citizens married to fellow U.S. citizens can transmit U.S. citizenship to their children if either parent has ever had a residence in the United States (without any minimum time limitation on how long they held that residence.) However, for U.S. citizens married to non-U.S. citizens, the required period of residence is longer; under the Nationality Act of 1940 and the Immigration and Nationality Act of 1952, the required period of residence was set to ten years, five of which had to be after the age of 14. The Immigration and Nationality Act Amendments of 1986 reduced this to five years, two of which had to be after the age of 14.
So you're automatically a citizen if you're born in the USA, if both of your parents are citizens (and at least one has resided in the USA), or if either of your parents is a citizen and lived in the USA for 5 years (2 of which after the age of 14).