Citizenship of the United States
A person who is considered a citizen by more than one nation has "dual citizenship". It is possible for a United States citizen to have dual citizenship; this can be achieved in various ways, such as by birth in the United States to a parent who is a citizen of a foreign country (or in certain circumstances the foreign nationality may be transmitted even by a grandparent) by birth in another country to a parent(s) who is/are a United States citizen/s, or by having parents who are citizens of different countries. Anyone who becomes a naturalized U.S. citizen is required to renounce any prior "allegiance" to other countries during the naturalization ceremony; however, this renunciation of allegiance renunciation of citizenship to those countries.
Passport
Although all U.S. citizens are also U.S. nationals, the reverse is not true. As specified in , a person whose only connection to the U.S. is through birth in an outlying possession (which is defined in as American Samoa and Swains Island, the latter of which is administered as part of American Samoa), or through descent from a person so born, acquires U.S. nationality but not U.S. citizenship. This was formerly the case in only four other current or former U.S. overseas possessions.