Canada–United States border

The Canada–United States border, officially known as the International Boundary, is the longest international border in the world. It is shared between Canada and the United States of America, the second and fourth largest countries by area respectively. The terrestrial boundary (including small portions of maritime boundaries on the Atlantic, Pacific, and Arctic coasts, as well as the Great Lakes) is 8,891 kilometres (5,525 mi) long, of which 2,475 kilometres (1,538 mi) is with Alaska. Eight Canadian provinces and territories (Yukon, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, and New Brunswick), and thirteen U.S. states (Alaska, Washington, Idaho, Montana, North Dakota, Minnesota, Michigan, Ohio, Pennsylvania, New York, Vermont, New Hampshire, and Maine) are located along the border.

History

The Treaty of Paris (1783)

The border originated with the Treaty of Paris in 1783, which ended the American Revolutionary War between Great Britain and the separating colonies which would form the United States. The 45th parallel was established as the border between Quebec and New York State (including what is now Vermont). The St. Lawrence River and the Great Lakes became the boundary further west (between what is now Ontario and the United States).