WebsterAshburton

Webster–Ashburton Treaty, signed on August 9, 1842, was a treaty between the United States and the United Kingdom that resolved several outstanding disputes after the Aroostook War of 1838–1839. It was negotiated by U.S. Secretary of State Daniel Webster and British diplomat Lord Ashburton (Alexander Baring). The agreement is also referred to as the Ashburton-Webster Treaty.

The treaty primarily settled the northeastern boundary between the United States and British North America, including the Maine–New Brunswick frontier, and established a framework for determining other disputed areas in the Northwest. It provided for the creation of a joint boundary commission to survey and mark the agreed lines, and it helped reduce tensions by offering concrete mechanisms for border administration and dispute resolution.

In addition to boundary provisions, the treaty included terms to cooperate in suppressing the Atlantic slave trade and to facilitate the extradition of criminals. These components reflected a broader effort to improve Anglo-American security cooperation and mutual interests beyond purely territorial questions.

The Webster–Ashburton Treaty effectively ended the immediate crisis generated by border disagreements and is often cited as a milestone in peaceful dispute resolution between the United States and Britain. It also left unresolved the Oregon boundary in the west, a matter later addressed by the Oregon Treaty of 1846. The agreement contributed to a period of improved relations and served as a model for subsequent diplomatic engagements between the two nations.