The Jus Soli rule applies if a person is born in the United States.
The Jus Soli is a Latin term meaning the law of the soil. It is the right of anyone born in the territory of a state to nationality or citizenship. It is associated with permissive citizenship rights and it is the most common means a person acquires citizenship of a nation.
The US follows the Jus Soli system to determine citizenship. Which means that if a person is born in the US and is subject to its jurisdiction is automatically considered US citizen.