Did the U.S. Buy Florida from Spain? Yes—Adams–Onís Treaty (1819)

True. The United States acquired Florida from Spain through the Adams–Onís Treaty (also called the Transcontinental Treaty), signed February 22, 1819, and ratified 1821.

Key Terms

• Spain ceded: East Florida and West Florida (all of present-day Florida)
• U.S. paid: $5 million — not in cash, but by assuming U.S. citizen claims against Spain up to $5 million
• Boundary defined: Sabine River → Red River → Arkansas River → 42nd parallel → Pacific (settling Louisiana Purchase western border)
• U.S. relinquished: Claims to Texas (west of Sabine River) — later basis for Mexican–American War tensions

Context

• Spain couldn't defend Florida against US pressure (Andrew Jackson's 1818 invasion)
• Spain focused on collapsing Latin American empire
• John Quincy Adams (SecState) and Luis de Onís (Spanish minister) negotiated
• Ratified 1821 after Mexican independence complicated Spanish approval

Aftermath

• Florida Territory organized 1822
• Statehood 1845 (27th state)
• Seminole Wars (1817–1858) followed as US removed Native nations

The treaty completed the US southeastern border and set the stage for westward expansion to the Pacific.