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.
Florida in the American Civil War
In early May 1865, Edward M. McCook's Union division was assigned to re-establish Federal control and authority in Florida. On May 13, G. W. Scott surrendered the last active Confederate troops in the state to McCook. 
On May 20, General McCook read Lincoln's Emancipation Proclamation during a ceremony in Tallahassee, officially ending slavery in Florida. That same day, his jubilant troopers raised the U.S. flag over the state capitol building. Tallahassee was the penultimate Confederate state capital to rejoin the Union. Austin, Texas rejoined the next month.