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.
1820s
At the beginning of the 1820s, the United States stretched from the Atlantic Ocean through to (roughly) the western edge of the Mississippi basin, though Florida, Michigan, Wisconsin and all present-day states fully west of the Mississippi had yet to be granted statehood. Two states were admitted to the union during this decade: Maine in 1820, and Missouri in 1821. The Adams–Onís Treaty, signed in 1819 and ratified by Spain in 1821, ceded Florida to the United States, and established a boundary between New Spain and the United States.