Answer :
The actual slogan was "Fifty-four Forty or Fight" and the number referred to the north parallel of 54°40′ - the US claim of the lands of the Pacific Northwest. The British (what would later become Canada) claim was at 42°. Basically, it meant that if the US doesn't get its claim, it will fight.
The claims were settled by the Oregon treaty in 1846.
The claims were settled by the Oregon treaty in 1846.