Changes

By 1843, increased American immigration on the Oregon Trail to the Territory made the border issue a burning one in Congress, where jingoists raised the slogan of “54 degrees 40 minutes or fight.” President James Polk, a supporter of Manifest Destiny with an eye also on the Mexican Southwest and California, was eager to settle the boundary of the Oregon Territory and proposed a settlement on the 49 degree line to Great Britain.

British Minister to Washington, Richard Pakenham, and Secretary of State James Buchanan, supported and encouraged by British Foreign Secretary Lord Aberdeen and Senator John C. Calhoun of South Carolina, worked out a compromise. With some minor modifications, which reserved the whole of Vancouver Island to Canada, Great Britain agreed to Polk’s suggestion. The Senate ratified the treaty by a vote of 41-14 on June 18, 1846. A later controversy over the precise boundaries in the Juan de Fuca Strait was resolved by international arbitration in favor of the United States.