A territorial dispute between the USA and Britain. Since 1818, Britain and the USA had agreed on joint occupation of the Oregon country, an area west of the Rocky Mountains running down into the valley of the Columbia River. However, as settlers moved up the Oregon Trail, pressure mounted for the territory to become part of the USA. The settlers wanted their northern boundary with the British to be to the north of Vancouver Island on the 54° 40′. parallel, and in 1844 President Polk used the slogan “54 40 or fight” in his victorious campaign. Discussions took place with the British, who at first insisted on the Columbia River as boundary. A compromise agreement between the British Foreign Secretary Lord Aberdeen and President Polk was reached in 1846. This was to accept a line well to the south of Polk’s original demands, extending the 49th parallel boundary to the Pacific, but excluding Vancouver Island. In 1848, Congress created the Oregon Territory. This was later split up into the state of Oregon (1859), the state of Washington (1889), the state of Idaho (1890), and parts of Montana and Wyoming.