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.
Spanish Florida
France sold Louisiana to the United States in 1803. The U.S. claimed that the transaction included West Florida, while Spain insisted that the area was not part of Louisiana and was still Spanish territory. In 1810, the United States intervened in a local uprising in West Florida, and by 1812, the Mobile District was absorbed into the U.S. territory of Mississippi, reducing the borders of Spanish Florida to that of modern Florida.