Minnesota/Canada border?

Question

Why does the Minnesota border turn North to incorporate an island in the Lake of the Woods, when it would seem more natural for it to run along the lake's Southern shore?

Answer 1

It has to do with the Treaty of 1818 between the US and Great Britain. Which set the border along the 49th Parallel from the from the Northwest point of Lake of the Woods to the Rock Mountains. But they didn't really know if that point was even on the 49th Parallel or not. So they decided the line would run due North or South (turned out to be South) to the 49th Parallel then due West to the Rocky Mountains.

Keep in mind that they didn't have any good maps of the area at that time. So basically they were clueless as to where that point even was. The result of which is the mess it is today.