This is a trick of scale and map projection. When asked which U.S. state has the longest border with Canada, most people choose Alaska. This is correct—Alaska’s border with Canada is 1,538 miles long. However, if the question is 'Which *contiguous* (lower 48) state has the longest border with Canada?', the answer is Michigan. Most people assume it is Montana or North Dakota, but because Michigan’s border runs through the middle of the Great Lakes (Superior, Huron, and Erie), its water border with Ontario is incredibly long, totaling 721 miles. This makes it longer than the land borders of any other northern state, a fact that emphasizes how often water boundaries are overlooked in geographical rankings.