why is the northwestern corner of minnesota not canada
The gents formulating the Treaty had a lousy map.
http://en.wikipedia.org/wiki/Northwest_Angle
The reason the northwestern corner of Minnesota is not part of Canada can be traced back to the Treaty of Paris in 1783. During the negotiations, the British and American delegates were using maps that were not very accurate. This led to a discrepancy in the boundary lines between the United States and Canada.
The Treaty of Paris defined the border between the United States and British North America (which later became Canada) as following a line from the northwest corner of Lake of the Woods to the Mississippi River. However, due to the inaccuracies of the maps used, the negotiators mistakenly believed that the northwest corner of Lake of the Woods was located further to the south than it actually is.
As a result, the border line was drawn in a way that extended from the northwest corner of the lake at a slant, creating a small section of land to the north that remained part of the United States. This area is known as the Northwest Angle, and it is the only part of the contiguous United States that is north of the 49th parallel, which acts as a significant part of the boundary between the United States and Canada.
In conclusion, the reason the northwestern corner of Minnesota is not part of Canada is primarily due to the inaccuracies of the maps used during the negotiation of the Treaty of Paris in 1783.