Citizenship at Birth
The Fourteenth Amendment states that all persons born in the U.S. are citizens. This includes people born in the U.S. territories of Puerto Rico and U.S. Virgin Islands.
There are exceptions to the birth rule. People born to foreign heads of state and diplomats are excluded. People born on foreign vessels and in some of the U.S. possessions are considered Nationals (entitled to live and work in the U.S., no right to vote).
Birth outside the U.S.
Depending on date of birth and the citizenship of the parents, a child born outside the U.S. will acquire citizenship at birth. The Government will consider the parental requirements and whether the birth was out of wedlock.
A dual citizenship allows a qualifying person to retain the citizenship in another country as well as in the U.S.