Adams-Onís Treaty

Signed in 1819 by John Quincy Adams and Luis de Onís, the Adams-Onís Treaty between the United States and Spain gave Florida to the U.S. and established the Sabine River as the border between the U.S. and New Spain. 

The formation of Texas was part of a global story. The boundaries of European land claims changed as a result of wars in Europe, revolutions in the colonies, and the birth of the United States. When the French sold Louisiana to America with the Louisiana Purchase in 1803, many Americans believed the sale included Texas. These claims were based on La Salle's failed attempt to colonize Texas in the 1680s. The Adams-Onís Treaty put those claims to rest, ceding Texas to Spain. However, many Americans did not agree with the treaty. Some U.S. citizens argued the border should be at the Rio Grande. Many individuals and families from the east settled in Texas illegally, which was still part of Spanish-controlled Mexico. 

This is the official U.S. version of the treaty. On February 22, 1819, John Adams wrote in his diary about the treaty’s signing: “Mr Onis came at eleven … We exchanged the original full powers on both sides … I had one of the copies of the Treaty, and Mr Onis the other — I read the English side which he collated, and he the Spanish side which I collated. We then signed and sealed both copies, on both sides; I first, on the English, and he first on the Spanish side: some few errors of copying, and even of translation were discovered, and rectified. It was agreed that the four other copies should be executed in two or three days, as soon as they are all prepared. Mr Onis took with him his executed copy of the Treaty, and I went over with ours to the President’s.”

Several other versions of the treaty exist as well, printed for general reference, for government use, or as evidence in court cases. In 1821, Baron de Bastrop translated the treaty into Spanish from a copy printed in the Louisiana Gazette for Spanish citizens in Texas who were eager to learn how the treaty would change their borders.