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(1846) (also Treaty of Washington), an agreement concluded between the USA and Great Britain on June 15, 1846. It resolved the dispute over possession of the territory extending from the Rocky Mountains to the Pacific Ocean between 42° and 54°40′ N lat.
Formally, by the terms of the 1818 agreement between the two countries, this territory had been jointly occupied. However, the Oregon Treaty provided for recognition of the territory north of the 49th parallel as a British possession; the land south of the 49th parallel went to the USA. Congress quickly ratified the treaty in view of the fact that the USA, involved in the Mexican War (1846–48), was in no position to go to war over Oregon.