The Oregon Territory started out under joint control by both Britain and America, but as more and more Americans moved into the area and trade began to suffer, the two countries negotiated a deal in which America became the sole owner of the territory. The negotiations were not easy, with different parties in the country calling for different strategies after the initial offer to split the territory at the 49th parallel failed. Members of Congress who were against slavery wanted to obtain as much of the territory as possible because any state created there would be a free state.
After the initial no, people in favor of expansion began to call for all of the territory or go to war for it. Neither nation wanted war, and the proslavery members of Congress refused to fund any kind of war against Britain for the Oregon Territory. The initial war cries called for land to be given up much further north than the 49th parallel. The final agreement did split the territory at that dividing line and managed to avoid war. The Oregon Territory eventually became the states of Oregon, Washington and Idaho. The area also covered smaller sections of Montana and Wyoming. These make up the states that run along the border of the United States and Canada.