Adams–Onís Treaty: Spain cedes Florida

Background. The treaty emerged from the context of the Seminole Wars, during which the US occupied Florida, creating an opportunity for favorable negotiations. Spain, prepared to accept the loss of Florida, sought a firm border in Texas. The agreement established the first transcontinental boundary for the United States, extending its claimed territory to the Pacific Ocean.

Negotiation. Negotiations involved significant diplomatic intervention, including the French ambassador Hyde de Neuville, who defended the Spanish position against radicalism in the US Congress. The process was complicated by the escalation of the Seminole War and the hostility of General Andrew Jackson towards the Spanish presence in East Florida. These factors shaped the terms agreed upon by the two powers.

Terms. The treaty stipulated that the boundary between French and Spanish claims followed the Red River to the 100th meridian. The United States acquired Florida while renouncing claims to Spanish Texas. This agreement defined the first transcontinental boundary, extending US territory west from the Mississippi River to the Pacific Ocean, building on previous conventions with Britain.