Six U.S. States Share an International Border—All With Canada

Contrary to common assumptions about the southern border, six U.S. states share an international land or water border—all with Canada. No U.S. state borders another country exclusively; the four Mexican border states (California, Arizona, New Mexico, Texas) are matched by thirteen Canadian border states, but only six have Canada as their sole international neighbor.

The Six States

1. Maine – 611-mile land border with Quebec and New Brunswick
2. Alaska – 1,538-mile border with Yukon and British Columbia (longest of any state)
3. Washington – 427-mile land border with British Columbia
4. Idaho – 45-mile border with British Columbia (northern panhandle)
5. Montana – 545-mile border with British Columbia, Alberta, and Saskatchewan
6. Michigan – Water border via Great Lakes (Superior, Huron, Erie) with Ontario

Why Only These Six?

Other northern states (Minnesota, North Dakota, Vermont, New Hampshire, New York, Ohio, Pennsylvania) also border Canada—but they share additional international boundaries:

• Minnesota, North Dakota, Montana border Canadian provinces but also have other distinctions
• Vermont, New Hampshire, New York border Quebec but are typically grouped with New England/Mid-Atlantic
• Ohio, Pennsylvania only have water borders via Lake Erie

The "six states" classification usually refers to states where Canada is the only foreign neighbor—excluding those with maritime boundaries or multiple international borders.

Border Significance

These borders facilitate:

• $600+ billion in annual U.S.-Canada trade
• Integrated supply chains (automotive, energy, agriculture)
• Cross-border communities with shared infrastructure
• Joint environmental management of Great Lakes and watersheds

Michigan's water-only border is unique—it's the only state whose international boundary is entirely aquatic, governed by the 1909 Boundary Waters Treaty.