During the late 18th and early 19th centuries, the area's legal and political status was disputed. The Treaty of Paris, which ended the American Revolutionary War in 1783, had defined the northern border between the United States and Canada based on the inaccurate Mitchell Map. Ownership of the area between Lake of the Woods and Lake Superior was unclear, with the United States claiming the border was further north at the Kaministiquia River and Canada claiming it was further south beginning at the Saint Louis River. In 1842, the Webster–Ashburton Treaty clarified the border between the United States and Canada using the old trading route running along the Pigeon River and Rainy River (today the BWCAW's northern border).