What did the famous political slogan,"54, 40' or Fight" mean?

While the United States fought to capture the Southwest, it also added lands in the Northwest. During the 1840s, more than 10,000 American pioneers began to move westward to Oregon and California. Also, in 1847, approximately 2,000 Mormons, who had trekked across the United States in search of a place in which to practice their religion, began to settle near the Great Salt Lake in present-day Utah.

President Polk was determined to add Oregon to the Union, a vast territory including the present-day states of Oregon and Washington. Both the U.S. and Great Britain claimed this territory. During the campaign of 1844, Polk had used the slogan "54 40' or Fight." By this he meant, 54 degrees, 40 minutes north latitude, which he considered the natural boundary of the Oregon territory.

He insisted that he would not compromise, and that the U.S. was determined to gain the entire Oregon territory. As president, however, Polk did compromise with Britain, accepting the 49th parallel (49 degrees north latitude) as the boundary between the U.S. and Canada. Even so, this was another enormous acquisition of land for the United States.