The slogan "Fifty-four forty or fight" originated during a dispute between the United States and Great Britain over the Oregon country. Under the terms of a treaty signed in 1818, both nations were permitted to occupy this territory. The boundary began at 42 degrees north latitude, the southern boundary of present-day Oregon; it extended north to 54 degrees 40 minutes north latitude, in present-day British Columbia. (Latitude is a geographical term for the angular distance north or south of Earth's equator.) During the 1830s and early 1840s, American expansionists (those who advocated expanding the United States into the West) insisted that U.S. rights to the Oregon country extended north to latitude 54 degrees 40 minutes. (A degree is a position or space in measuring latitude; a minute is the sixtieth part of a degree.) At the time this was the recognized southern boundary of Russian America (part of present-day Alaska).
In 1844 James K. Polk (1795–1849) used "Fifty-four forty or fight" to rally supporters in his successful presidential campaign. Two years after Polk took office as president he settled the dispute with Great Britain; the boundary was then set at 49 degrees north, the northern boundary of present-day Washington State and the border between the United States and Canada. This agreement, which was reached without the fight Polk threatened in his slogan, gave the United States control over land lying between 42 and 49 degrees north latitude (present-day Washington, Oregon, and Idaho as well as parts of Montana and Wyoming). Great Britain was granted the territory between 49 degrees and 54 degrees 40 minutes north latitude as well as Vancouver Island.
Further Information: Greenblatt, Miriam. James K. Polk, 11th President of the United States. Ada, Okla.: Garrett Educational Corporation, 1988; Grolier Incorporated. "James Polk." The American Presidency. http://gi.grolier.com/presidents/ea/bios/11ppolk.html, October 25, 2000; James K. Polk. [Online] Available http://www.whitehouse.gov/WH/glimpse/presidents/html/jp11.html, October 25, 2000.