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.
West Florida
On February 22, 1819, Spain and the United States signed the Adams-Onís Treaty. In this treaty Spain ceded both West and East Florida to the United States in exchange for compensation and the renunciation of American claims to Texas. Following ratification by Spain on October 24, 1820, and the United States on February 19, 1821, the treaty took effect, thereby establishing the current boundaries.