United States territorial acquisitions
West Florida was declared to be a U.S. possession in 1810 by President James Madison after the territory had declared its independence from Spain. Madison ordered the U.S. Army to take control. Six weeks later, the army entered and occupied the capital, St. Francisville, putting an end to the republic after 74 days of independence. Spain did not relinquish its claim to sovereignty (see West Florida Controversy) until ratification of the Adams–Onís Treaty. General Andrew Jackson personally accepted the delivery of West Florida from its Spanish governor on July 17, 1821.
Key West
On March 25, 1822, Lt. Commander Matthew C. Perry sailed the schooner "Shark" to Key West and planted the U.S. flag, claiming the Keys as United States property. No protests were made over the American claim on Key West, so the Florida Keys became the property of the United States.