America follows the English common law rule of "right of soil." In short, citizenship is determined by one's place of birth. Those born in the U.S. or its territories (like Puerto Rico, the Virgin Islands and Guam), are American citizens regardless of their parents' citizenship status.However, U.S. installations in foreign countries are not considered part of the United States. So, delivering a baby at a U.S. naval base or embassy in a foreign country does not entitle the baby to U.S. citizenship.