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.
1820s
At the beginning of the 1820s, the United States stretched from the Atlantic Ocean through to (roughly) the western edge of the Mississippi basin, though Florida, Michigan, Wisconsin and all present-day states fully west of the Mississippi had yet to be granted statehood. Two states were admitted to the union during this decade: Maine in 1820, and Missouri in 1821. The Adams–Onís Treaty, signed in 1819 and ratified by Spain in 1821, ceded Florida to the United States, and established a boundary between New Spain and the United States.