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.
Polk County, Florida
While Florida gained statehood in 1845, it was not until 1861 that Polk County was created from the eastern part of Hillsborough County. It was named in honor of former US President James K. Polk, whose 1845 inauguration was on the day after Florida became a state.