Which provinces share the border with the United States?

Canada and the United States share the longest international border in the world, running 8,891 kilometres including the maritime border in the Great Lakes and the offshore boundary, and 6,416 kilometres on the continental border excluding maritime sections. Eight Canadian provinces and all three territories share land or water borders with the United States. The three Canadian provinces without a direct US border are Nova Scotia, Prince Edward Island, and Newfoundland and Labrador.

British Columbia borders Washington State along the 49th parallel of north latitude (which serves as the international boundary across most of western Canada) and Alaska along the Alaska Panhandle (the 1903 Alaska Boundary Tribunal settled the long-disputed coastal boundary). Alberta borders Montana along the 49th parallel. Saskatchewan borders Montana and North Dakota along the 49th parallel. Manitoba borders North Dakota and Minnesota along the 49th parallel.

Ontario has the longest provincial-US border, sharing water and land boundaries with Minnesota (across the Pigeon River and Lake Superior), Michigan (across Lake Superior, the St. Marys River, Lake Huron, the St. Clair River, Lake St. Clair, and the Detroit River), Ohio and Pennsylvania (across Lake Erie), New York (across Lake Erie, the Niagara River, Lake Ontario, and the St. Lawrence River). Quebec borders Maine, New Hampshire, Vermont, and New York. New Brunswick borders Maine.

The three territories all have land or water boundaries with the United States. Yukon shares a land border with Alaska (the 141st meridian, surveyed between 1904 and 1920). The Northwest Territories does not directly border the United States across land, but its Beaufort Sea waters border the Alaska maritime zone (with an active boundary dispute over the orientation of the border line). Nunavut shares maritime boundaries with Alaska in the Beaufort Sea and with Greenland (a Danish territory) in Davis Strait, Baffin Bay, and Nares Strait. The Hans Island (Tartupaluk) boundary dispute between Canada and Denmark was settled by treaty signed June 14, 2022, dividing the small island between the two countries.