Canada and the United States share the longest border on earth.
It is also one of the strangest borders on earth.
For example, there is a 20-foot wide space along the border.
There is still some disputed territory. Vancouver Island, which the 49th parallel would have sliced through, but both sides agreed that would be dumb so the border swoops around the island.
There is a series of islands in the Atlantic that the United States claims are part of Maine and Canada claims are part of New Brunswick.