Alaska.
Alaska
Since North Dakota and Canada share a border, the drive would be longer from South Dakota to Indiana.
Montana [877 km/545 mi] has a longer border with Canada than North Dakota [499 km/310 mi].
Montana has a longer border than New York, but Alaska has the longest border.
Alaska is the US state with longest Canadian border.
Montana has a longer border than New York, but Alaska has the longest border.
Montana has a longer border than New York, but Alaska has the longest border.
South Dakota to Canada
Minnesota's border with Canada is longer than North Dakota's border. The boundary between the US state of North Dakota and the Canadian Provinces of Manitoba and Saskatchewan is 310 miles (499 km) long. The boundary between the US state of Minnesota and the Canadian Provinces of Manitoba and Ontario is 547 miles (880 km) long.
Alaska is the US state which shares the longest border with Canada.
Montana is longer of those 2 states. But Alaska, Michigan, Maine and Minnesota are longer still.