The Northwest Angle owes its existence to Benjamin Franklin, US Minister Plenipotentiary at the negotiations for the Treaty of Paris (1783). Franklin’s efforts won British acceptance for the US-British border to extend “from the most northwesternmost point” (sic) of the Lake of the Woods to the Boundary Waters (i.e. towards the east), and from that point due west to the Mississippi.The interesting article in the Strange Maps blog at Big Think points out that there is a second anomalous area - Elm Point.
As the negotiators in Paris used the faulty Mitchell Map (which showed the Mississippi mistakenly extending too far north beyond its actual source at Lake Ithasca), such a line could not be drawn. Therefore, after the 49th parallel had been agreed as the line dividing American and British possessions west of Lake of the Woods, in 1818 a line was drawn due south from that northwesternmost point towards the 49th parallel. Hence the 90-degree upward bend in that border, creating, as the handful of locals call it, ‘The Angle’.
Point Roberts and the Northwest Angle are not the only border anomalies on the 49th parallel. A much smaller American exclave exists only a few feet from the aforementioned 90-degree bend... The 49th-parallel line skirts Buffalo Point’s southern shore... the peninsula to the south of the line is US soil, cut off from its main territory by American water and Canadian land. Unlike Point Roberts, this much smaller peninsula is uninhabited. The actual border, visible on Google Maps as a line cut clear through the pine forest, is a mere 3,400 feet long... This box-shaped border anomaly is known as Elm Point. It is part of Roseau County in Minnesota, unlike Northwest Angle, which is part of Lake of the Woods County...
Exclaves are territories legally part of a country but not physically attached to them. Enclaves are territories entirely contained within another country. While both categories often overlap, they are not the same. Lesotho is an enclave within South Africa, but not an exclave of another country. The territories mentioned here are exclaves of the US, but not enclaved within Canada (as they have access to the US over water).You learn something every day.
Map credit: Ruland Kolen