Four years after the end of the War of 1812, Great Britain and the United States agreed that their citizens could trade in Oregon country without prejudice to either nation's claim, and both countries sought influence there that could grow into sovereignty. The Oregon Question became a matter of increasing concern and by the early 1840s had become a major dispute. In the 1844 presidential campaign, James K. Polk made settlement of the Oregon boundary question a central issue, while the activist Northwestern U.S. Senator Lewis Cass coined the slogan "All Oregon or none, 54-40 or fight." In 1823, the United States and Imperial Russia had agreed to limit their spheres of influence to fifty-four degrees, forty minutes north latitude, today's boundary between Alaska and Canada. War between Great Britain and the United States was avoided on June 15, 1846, when the Convention of Washington resolved the Oregon Question by establishing the 49th parallel as the international boundary.