Who decided the 49th parallel?

The 49th parallel was established as a boundary between the United States and British North America (now Canada) through the Oregon Treaty of 1846, negotiated by U.S. Secretary of State James Buchanan and British diplomat Sir Richard Pakenham. This decision was influenced by previous treaties, such as the Treaty of Ghent, and ongoing negotiations over territorial claims in the Pacific Northwest. The boundary was chosen to resolve disputes and provide a clear demarcation between the two nations.