The treaty of “Amity, Settlement and Limits” by which Spain ceded the Floridas (East and West) to the United States, was concluded and signed on February 22, 1819, but ratifications were not exchanged until February 22, 1821 - both transactions coincidentally being on the anniversary of George Washington’s birth. On March 10, 1821, General Andrew Jackson was appointed to take over the Floridas from Spain, and assume their government pending their formal creation as a territory of the Union. The commission bestowed upon him the title: Governor of the Floridas, exercising all the powers and authorities heretofore exercised by the governor, and captain-general, and intendant of the island of Cuba, and by the governors of East and West Florida within the said provinces, respectively.
Davis, T. Frederick
"Pioneer Florida: Jackson’s Premature Proclamation, 1821,"
Florida Historical Quarterly: Vol. 24
, Article 7.
Available at: https://stars.library.ucf.edu/fhq/vol24/iss1/7