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
On January 10, 1861, nearly all delegates in the Florida Legislature approved an ordinance of secession, declaring Florida to be "a sovereign and independent nation"—an apparent reassertion to the preamble in Florida's Constitution of 1838, in which Florida agreed with Congress to be a "Free and Independent State." Although not directly related to the issue of slavery, the ordinance declared Florida's secession from the Union, allowing it to become one of the founding members of the Confederate States, a looser union of states.