Montana
The western states in the 48 contiguous states that have the longest border with Canada are Washington and Montana. Washington shares a border with British Columbia, while Montana shares a border with Alberta, Saskatchewan, and British Columbia.
Montana
montana, 48 degrees
Florida has the largest water border.
In the west, the state of Montana has the longest linear border with Canada. In the east, the state of Michigan has the longest border, including the Great Lakes.
The Pacific Ocean
Contiguous is an adjective describing things that share a common border, are touching, or things together in a sequence. Example: The United States and Canada share a contiguous border.
Canada is the 2nd largest COUNTRY in the world, and does not belong to the United States in any way. It just happens to share a northern border with the contiguous states.
Canada touches the entire northern border of the 48 contiguous United States, and the whole eastern border of Alaska.
At 8891 km, the border between Canada and the USA is the longest between any two countries, but a major section of that border (with Alaska) is not contiguous with the rest. The longest contiguous section of border between two countries in the world is between Russia and Kazakhstan, at 6846 km.
Canada has the largest border to the USA.