ADAMS-ONIS TREATY

The Adams-Onis Treaty, officially called the Transcontinental Treaty, was signed in 1819 by the United States and Spain. The treaty, which was ratified on February 21, 1821, settled boundary disputes between the two countries. The terms of the earlier Louisiana Purchase (1803) failed to specify fully the boundaries of the territory that the United States had acquired from France. Britain and the United States soon disagreed over the Louisiana Territory's northern boundary. Spain and the United States reached an impasse over where the boundary lay between the U.S. territory and Spanish America—Spain's possessions in Florida, along the Gulf Coast, and in the Southwest. The terms of the Adams-Onis Treaty were negotiated by U.S. Secretary of State (later elected president) John Quincy Adams (1767–1848) and Spanish Minister to the United States Luis de Onis (1762–1827). The treaty established the line of demarcation between the new republic and Spanish territorial claims. The countries agreed that the western boundary of the United States began at the mouth of the Sabine River (which today forms the border between western Louisiana and eastern Texas). From there the boundary ran at a northwest angle until it reached 42 degrees north latitude. It then followed this line of latitude west to the Pacific Ocean. Territory lying east and north of this line belonged to the United States; territory lying west and south of this line belonged to Spain. By this treaty the United States gained all of Florida and a southern strip of Alabama and Mississippi (collectively called the Old Southwest). Spain retained its claim to the Southwest, which was roughly the area of present-day Texas, New Mexico, Colorado, Utah, Arizona, Nevada, and California. As part of the treaty, the United States agreed to pay $5 million in claims of U.S. citizens against Spain. The claims were made by people who had settled Florida, predominately the panhandle (then called West Florida), while it was still a possession of Spain.

See also: Convention of 1818, Louisiana Purchase, Manifest Destiny, Old Southwest

Adams‐Onís Treaty (1819)This agreement, also called the Transcontinental Treaty, was made during the administration of President James Monroe and settled long‐standing disputes between the United States and Spain. Madrid ceded East Florida to the Americans, while Washington surrendered its claims to Texas and agreed to assume payment of American financial claims against the Spanish up to $5 million. The treaty established definitive western boundaries for the Louisiana Purchase, following the Sabine, Red, and Arkansas Rivers to the 42nd parallel, and running along that line to the Pacific. The United States also secured Spanish claims to Oregon.

Historians have variously interpreted the treaty's significance. Samuel F. Bemis stressed the establishment of the first American claims to territory bordering the Pacific. More recently, William E. Weeks emphasized that the treaty consummated the first phase of the United States's aggressive, nineteenth‐century territorial expansion. Strategically speaking, the Florida cession closed a vulnerable point in American coastal defenses. European powers welcomed the treaty because it ended the possibility of war between the United States and Spain. Some westerners protested the loss of Texas, but otherwise, there was little domestic opposition. The agreement was named for its principal negotiators—Secretary of State John Quincy Adams and Spain's minister to the United States, Don Luis de Onís.
[See also Expansionism.]

Bibliography

Charles C. Griffin , The United States and the Disruption of the Spanish Empire, 1810–1822, 1937.
Philip C. Brooks , Diplomacy and the Borderlands: The Adams‐Onís Treaty of 1819, 1939.
Samuel Flagg Bemis , John Quincy Adams and the Foundations of American Foreign Policy, 1949.
William E. Weeks , John Quincy Adams and American Global Empire, 1992.

Michael S. Fitzgerald

Adams-Onís Treaty (February 22, 1819) Agreement between the USA and Spain. Negotiated by secretary of state John Quincy Adams and Spanish minister Luis de Onís, Spain gave up its land e of the Mississippi River and claims to the Oregon Territory; the US assumed debts of US$5 million and gave up claims to Texas.