What did the fifty-four forty or fight mean?

Answer 1

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 the territory. The territory began at 42° north latitude, the southern boundary of present-day Oregon; it extended north to 54° 40' (54.66°) north latitude, in present-day British Columbia. At the time this was the recognized southern boundary of Russian America (later purchased by the US in 1867 as 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.

*As this issue was settled, the US began its war with Mexico, further extending the concept of Manifest Destiny regarding US territorial claims in North America.