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
Because of disagreements with the Spanish government, American and English settlers between the Mississippi and Perdido rivers declared that area as the independent Republic of West Florida in 1810. (None of the short-lived Republic lay within the borders of the modern U.S. state of Florida; it comprised the Florida parishes of today's Louisiana.) Within months it was annexed by the United States, which claimed the region as part of the Louisiana Purchase of 1803. In 1819 the United States negotiated the purchase of the remainder of West Florida and all of East Florida in the Adams–Onís Treaty, and in 1822 both were merged into the Florida Territory.