Which parallel forms much of the border between Canada and the USA?
Canada–United States border drawing a border between British North America (later Canada) and the United States. Westward expansion of both British North America and the United States saw the boundary extended west along the 49th parallel from the Northwest Angle at Lake of the Woods to the Rocky Mountains under the Treaty of 1818. That treaty extinguished British claims south of that latitude to the Red River Valley, which was part of Rupert's Land. The treaty also extinguished U.S. claims to land north of that line in the watershed of the Missouri River, which was part of the Louisiana Purchase; this amounted to
48th parallel north 48th parallel north The 48th parallel north is a circle of latitude that is 48 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean. The Boston Beer Company brews an India Pale Ale called "Latitude 48" as much of the Northern Hemisphere's hops are grown in a belt at approximately this latitude. In Canada the parallel forms part of the border between Quebec and New Brunswick. Ships heading north along the coast of Washington toward the Strait of Juan de Fuca must make radio contact with Canadian Coast Guard