Answer:
The Convention of 1818 was an international treaty between the United States and the British Empire, signed in London on October 20, 1818, defining the border between the independent United States and the central part of British North America.
The convention traced the border between Lake of the Woods and the Rocky Mountains by following the route of the 49th parallel north, thus fixing the limit of the Missouri Territory. This was extended further west in 1846 when the Oregon Treaty was signed, extending the American-Canadian border through the 49th parallel to the Pacific Ocean.