The acquisition of Florida from Spain by the United States, formalized in 1819 and ratified in 1821, is a pivotal event in American history often examined in Advanced Placement United States History (APUSH) curricula. The agreement involved Spain ceding Florida to the U.S. in exchange for the U.S. assuming claims of American citizens against Spain up to $5 million and relinquishing its own territorial claims west of the Sabine River, effectively defining the southwestern border with Spanish territory. This event is often referred to as the Adams-Ons Treaty, named after the U.S. Secretary of State John Quincy Adams and the Spanish minister Luis de Ons, who negotiated the terms.
This diplomatic achievement held significant implications for the United States. It eliminated a persistent source of conflict along the southern border stemming from Seminole raids and runaway slaves seeking refuge in Spanish Florida. Furthermore, it expanded U.S. territory, providing access to valuable resources and strategic ports along the Gulf Coast. The treaty’s resolution of boundary disputes with Spain also strengthened American national security and facilitated westward expansion. The historical context includes Andrew Jackson’s military incursions into Florida, which, while controversial, demonstrated Spain’s inability to control the territory and pressured them to negotiate.
