The United States dollar is not exclusively used in the United States.
The dollar coin is a United States coin worth one United States dollar . United States dollar . The United States dollar ( sign : $ ; code : USD ; also abbreviated US$ and referred to as the dollar , U.S. dollar , or American dollar ) is the official currency of the United States and its insular territories per the United States Constitution . Since the currency is the most used in international transactions , it is the world 's primary reserve currency . Besides the United States , it is also used as the sole currency in two British Overseas Territories in the Caribbean : the British Virgin Islands and Turks and Caicos Islands .