The U.S. first made its claims to the Oregon Territory when the Louis and Clark expedition made their way to the Oregon Coast. They assumed many other Americans would soon follow, but the terrain was deemed to dangerous for many years.
The Oregon Trail
In 1819, the nations of Russia, Spain, Great Britain, and the U.S. all had claims to the Oregon Territory. But by 1825, Russia and Spain redacted their claims and the U.S. and Britain agreed to joint occupation.
Affecting the Campaign
After an easy passage was found through the South Pass, "Oregon Fever" spread throughout the states. Early settlers wrote letters overexaggerating the opportunities provided in Oregon.
Keeping the Peace
In 1843, over 1000 pioneers set out on the Oregon Trail, headed for new opportunities. The journey was labor-intensive, however, and often fatal.
The debate over whether or not the U.S. should continue the treaty with Great Britain over Oregon helped fuel the presidential election of 1844. James Polk was able to sway the voters with slogans like, "All of Oregon or none!"
However, Polk wasn't prepared to go to war with England. Instead, he agreed to a diplomatic compromise that kept the peace treaty intact.