Oregon Boundary Dispute

The Oregon boundary dispute, or the Oregon Question, arose as a result of competing British and American claims to the Pacific Northwest of North America in the first half of the 19th century. Both the United Kingdom (UK) and the United States (USA) had territorial and commercial aspirations in the region as well as residual claims from treaties with Russia and Spain. The British knew the region as the Columbia District, a fur-trading division of the Hudson's Bay Company (HBC), while Americans referred to it as the Oregon Country. The broadest definition of the disputed region was defined by the following: west of the Continental Divide of the Americas, north of the 42nd parallel north (the northern border of New Spain and after 1821 of Mexico), and south of the parallel 54°40′ north (the southern border of Russian America after 1825).

The Oregon Dispute became important in geopolitical diplomacy between the British Empire and the new American Republic. In 1844 the U.S. Democratic Party, appealing to expansionist sentiment and the popular theme of manifest destiny, asserted that the U.S. had a valid claim to the entire Oregon Country up to Russian America at parallel 54°40′ north. Democratic presidential candidate James K. Polk won the 1844 election, but then sought a compromise boundary along the 49th parallel, the same boundary proposed by previous U.S. administrations. Negotiations between the U.S. and the British broke down, however, and tensions grew as American expansionists like U.S. Senator Edward A. Hannegan of Indiana, or Congressman Leonard Henly Sims, Missouri, which urged Polk to annex the entire Oregon Country north to the parallel 54°40′ north, as the Democrats had called for in the election. The turmoil gave rise to slogans like "Fifty-four Forty or Fight!" and the catchphrase "Manifest Destiny".

The expansionist agenda of Polk and the Democratic Party created the possibility of two different, simultaneous wars, because relations between the United States and Mexico were deteriorating following the annexation of Texas. Neither Britain nor the United States really wanted to fight a third war in 70 years. Just before the outbreak of the war with Mexico, Polk returned to his earlier position on the Oregon boundary and accepted a compromise along the 49th parallel as far as the Strait of Georgia. This agreement was made official in the 1846 Oregon Treaty, and the 49th parallel remains the boundary between the United States and Canada west of Lake of the Woods, other than the marine boundary which curves south through the Haro Strait (settled over the Rosario Strait in 1872) to the Strait of Juan de Fuca and so excludes from the United States Vancouver Island and the Gulf Islands. As a result, much of Point Roberts (a small peninsula extending south into the Strait of Georgia from Canada) is an exclave of the United States.