What did "54 * 40' or fight " mean?

Answer: The phrase "54 40 or Fight" was a slogan created by Democratic nominee James K. Polk in an attempt to rally the public in support of removing control of portions of the United States, including Texas, California and Oregon, from the British.

Polk called for expansion that included Texas, California, and the entire Oregon territory. The northern boundary of Oregon was the latitude line of 54 degrees, 40 minutes. "Fifty-four forty or fight!" was the popular slogan that led Polk to victory against all odds.