Despite the famous slogan “54-40 or fight,” used to promote the Democrats’ 1844 platform of settling the Oregon boundary dispute, James K. Polk and most of the United States government in 1845 did not actually want to go to war over the Oregon territory. This was especially true at a time when a much more profitable war seemed to be on the horizon–the war with Mexico.
Fighting a war with Great Britain would be far more costly than one against the fledgling Mexican Republic, and there was more land to be gained from Mexico than there was from Britain. Polk’s assessment of the situation proved to be correct, as 529,000 square miles were won in the Mexican Cession, whereas the territory lost by opting for the 49th parallel rather than 54-40 amounted to only about a fifth of that size.
Moreover, the United States and Great Britain were important trading partners to their mutual advantage, and conflict over the territory would reduce or eliminate that benefit. A diplomatic resolution, on the other hand, would strengthen the ties between the two countries and continue to build an amicable relationship. It had been thirty years since the war of 1812 and a continuation of the peace was in everyone’s interest.
As such, splitting the territory was the best option. Even most of the more hawkish members of congress favored only a war with Mexico, not one with Britain as well. So the Oregon Treaty, negotiated by Secretary of State James Buchanan and British envoy Richard Pakenham, was ratified and the United States secured the undisputed title to what is now the states of Idaho, Washington, and Oregon.