What is the longest distance from country to country?

The Longest International Land Border in the World

Spanning an astonishing 8,900 kilometers (5,530 miles), the international land border between the United States and Canada stands as the world’s longest. This colossal boundary stretches across the vast northern reaches of both nations, encompassing the contiguous United States and the state of Alaska.

The border’s origins can be traced back to the Treaty of Paris, signed in 1783, which defined the boundary as “a line to be drawn along the middle of the river Mississippi.” However, subsequent treaties and agreements refined and adjusted this line over time.

The border consists of three distinct segments:

• Eastern Segment: Runs from the Atlantic Ocean in Maine to the Great Lakes region in Ontario. Spanning approximately 4,259 kilometers (2,646 miles), it is the longest of the three segments.
• Central Segment: Extends from the western end of the Great Lakes to the Rocky Mountains in Montana and Alberta. Measuring 2,500 kilometers (1,553 miles), it is the shortest segment.
• Western Segment: Follows the crest of the Rocky Mountains from Montana to the Pacific Ocean in Washington and British Columbia. Spanning 2,141 kilometers (1,330 miles), it is the second-longest segment.

Along its length, the border crosses numerous rivers, lakes, and mountain ranges. It passes through diverse geographic regions, from dense forests and rolling hills to rugged mountains and frozen tundras. The border is also home to a wide variety of wildlife, including bears, wolves, moose, and elk.

The US-Canada border is a testament to the enduring relationship between the two nations. It serves as a boundary of separation but also as a bridge of cooperation and exchange. The flow of goods, people, and ideas across this border has shaped the history and culture of both countries.