The Adams–Onís Treaty of 1819, also known as the Transcontinental Treaty, the Florida Purchase Treaty, or the Florida Treaty, was a treaty between the United States and Spain in 1819 that ceded Florida to the U.S. and defined the boundary between the U.S. and New Spain. It settled a standing border dispute between the two countries and was considered a triumph of American diplomacy. It came in the midst of increasing tensions related to Spain's territorial boundaries in North America ...