Maritime history of Florida
Spain ceded Florida to the United States as part of the Adams–Onís Treaty of 1819, and Florida became a U.S. territory in 1821. Coastal trade with other markets continued to expand and towns like Jacksonville, Pensacola and Tampa became important ports. After becoming a U.S. territory, the federal government began building a series of lighthouses as aids to navigation along the coasts of Florida to mark dangerous headlands, shoals, bars and reefs.
Republic of West Florida
The United States did not recognize the independence of the Republic of West Florida, and on October 27, 1810, President James Madison of it, on the basis that it was part of the Louisiana Purchase. In his proclamation, Madison invoked the portion of the Louisiana Purchase agreement that directly quoted the 1800 St. Ildefonso treaty between France and Spain: Louisiana, Madison stated, had "the same extent that it had in the hands of Spain, and that it had when France originally possessed it." However, neither the 1800 treaty nor the 1803 purchase includes the word "originally"; instead, they state, "with the same extent that it now has in the hands of Spain and that it had when France possessed it." Madison's tweak served his annexation rationale but had no basis in the treaty language.