Why was the boundary between Canada and the United States set at the 49th parallel in 1846?

The boundary between Canada and the United States was established at the 49th parallel in 1846 through the Oregon Treaty to resolve a long-standing territorial dispute over the Oregon Country.12

For years, the region had been under joint occupation by Great Britain and the United States. Tensions rose as American immigration to the area increased, and some U.S. officials, including those driven by the concept of Manifest Destiny, pushed for control of the entire territory. The threat of war over these competing claims prompted a diplomatic resolution.13452

By agreeing to the 49th parallel, both nations successfully avoided conflict and finalized the border from the Rocky Mountains to the Pacific coast. This agreement recognized Vancouver Island as solely British territory, securing it as a base for the Hudson’s Bay Company.1432