You can't get There from Here

There are several places in America where, if using public roads, you must go through Canada to access the rest of America. There are also a few places in Canada where you must go through the US to access the rest of Canada. Ask Metafilter explains.

• Northwest Angle, Minnesota
• Alburgh, Vermont
• Point Roberts, Washington
• Estcourt, Maine - where there are private roads into Maine leading through the woods, buildings straddling the border and only four houses completely in the US
• Part of the St Regis Mohawk Reservation is in Quebec, but is only connected by road to the rest of the reservation in New York, not to anywhere within Quebec
• Campobello Island is Canadian, but is only connected by bridge to the eastern most point of the US: Lubec, Maine.