A provision of the Treaty of 1818 that expanded the United States also

The Treaty of 1818 set the boundary between the United States and British Canada along the 49th parallel from the Lake of the Woods west to the Rocky Mountains. This agreement helped define and expand U.S. territory, so the correct choice is “set the US-Canada border at the 49th parallel.” The United States and Britain shared access to the Oregon Country rather than giving it solely to the United States.

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