The Convention respecting fisheries, boundary and the restoration of slaves between the United States of America and the United Kingdom of Great Britain and Ireland, also known as the London Convention, Anglo-American Convention of 1818, Convention of 1818, or simply the Treaty of 1818, was a treaty signed in 1818 between the United States and the United Kingdom. Signed during the presidency of James Monroe, it resolved standing boundary issues between the two nations. The treaty allowed for joint occupation and settlement of the Oregon Country, known to the British and in Canadian history as the Columbia District of the Hudson's Bay Company, and including the southern portion of its sister district New Caledonia.

The two nations agreed to a boundary line involving the 49th parallel north, in part because a straight-line boundary would be easier to survey than the pre-existing boundaries based on watersheds. The treaty marked both the United Kingdom's last permanent major loss of territory in what is now the Continental United States and the United States' only permanent significant cession of North American territory to a foreign power. Britain ceded all of Rupert's Land south of the 49th parallel and west to the Rocky Mountains, including all of the Red River Colony south of that latitude, while the U.S. ceded the northernmost tip of the territory of Louisiana above the 49th parallel.