亚当斯-奥尼斯条约

The Adams–Onís Treaty was an agreement between Spain and the United States, signed February 22, 1819, by John Quincy Adams and Luis de Onís respectively. The United States acquired Florida while renouncing claims to Spanish Texas and establishing its first transcontinental boundary.

The provisions of the treaty remained in full effect only until August 24, 1821, when the Treaty of Córdoba acknowledged Mexican independence from Spain. In the 1828 Treaty of Limits (Mexico–United States), the border defined by the Adams–Onís Treaty was recognized as the boundary between Mexico and the US, although following the 1845 Texas annexation, it was amended again by the Treaty of Guadalupe Hidalgo. The Adams–Onís Treaty was formally terminated in 1902.

Background

Pinckney's Treaty of 1795 established borders between the United States and Spanish Florida, but expansion by American settlers into this region led to ongoing disputes between the countries. The 1803 Louisiana Purchase caused further arguments over whether the new boundary to the south ran along the Sabine River, or the Rio Grande.

The outbreak of the Peninsular War in 1807 and the Spanish American wars of independence in 1808, undermined Madrid's ability to retain its American territories. Between 1810 and 1813, the US took advantage to annex West Florida in piecemeal fashion from the Mississippi east to the Perdido River, the modern state boundary with Alabama.

During the first of the Seminole Wars from 1817 to 1818, the US occupied the rest of Florida, presenting John Quincy Adams, then Secretary of State, an opportunity to negotiate favorable terms. His policy was to simultaneously avoid foreign commitments, but to also establish the US as the preponderant power on the North American continent. This required the elimination as far as possible of competing Spanish, Russian and British interests in the region, and extending the limits of American power to the Pacific. These principles were set out in more detail in the 1823 Monroe Doctrine.

Provisions

Negotiations were held in Washington, D.C., led by Adams for the United States, and Luis de Onís, the Spanish ambassador, resulting in a final agreement of 16 articles.

Key provisions included Article 2, transferring East and West Florida to the US, and Article 3, defining the southern border between the two countries, while Spain withdrew historic claims to the Oregon Country. Other terms included an agreement by the US government to compensate American settlers for alleged losses inflicted by the Spanish, the continuation of Pinckney's Treaty, and most favoured nation privileges for Spanish traders in Pensacola and St. Augustine for twelve years.

Implementation

The U.S. Senate approved the treaty unanimously on February 24, 1819, but Madrid delayed ratification until October 1820, hoping to dissuade the US from supporting anti-Spanish revolutionaries. As a result of the delay, the Senate had to vote a second time, at which point Henry Clay and others demanded the cession of Texas in addition. This proposal was defeated and the treaty officially made effective on February 22, 1821.

In accordance with Article 11, the US government set up a commission to handle claims made by private American citizens against Spain, which distributed around $5 million prior to its dissolution in 1824.

For the United States, this Treaty (and the Treaty of 1818 with Britain agreeing to joint control of the Pacific Northwest) meant that its claimed territory now extended far west from the Mississippi River to the Pacific Ocean. For Spain, it meant that it kept its colony of Texas and also kept a buffer zone between its colonies in California and New Mexico and the U.S. territories. Many historians consider the Treaty to be a great achievement for the U.S., as time validated Adams's vision that it would allow the U.S. to open trade with the Orient across the Pacific.