The Oregon Treaty of 1846: Definition & Summary

Instructor: Christina Boggs

Chrissy has taught secondary English and history and writes online curriculum. She has an M.S.Ed. in Social Studies Education.

Did you know that the Oregon Territory was claimed by not just the United States, but three other countries as well? This lesson explains the origins and terms of the Oregon Treaty of 1846.

The Oregon Territory

During the 1800s, the United States was not as big as it is today. Thomas Jefferson made the Louisiana Purchase in 1803 that more than doubled the size of the country. The Louisiana Territory, however, did not extend all the way to the west coast. While the area that makes up California today was owned by Spain, the Oregon Territory was up for grabs. The Oregon Territory started at the Pacific Ocean and stretched all the way inland to the Rocky Mountains, covering the area you know today as Washington and Oregon in the U.S., and British Columbia in Canada. The United States was very interested in that land, and Great Britain, Spain, and Russia had their sights set on it, too!


Each of the interested countries had their own specific claims to the Oregon Territory. The United States believed they had a right to that land because the Lewis and Clark Expedition had explored much of it on their way to the Pacific Ocean. The Pacific Fur Company (owned by an American) also had a trading post located in the region. At the same time, Great Britain believed the Oregon Territory was theirs because Captain James Cook had explored the Columbia River that flows between present-day Washington and Oregon. Meanwhile, Russia tried to create a fishing and whaling monopoly in the area. Spain officially gave up its claims to the Oregon Territory in 1819 after signing the Transcontinental Treaty with the United States

The United States and Great Britain

In 1818, the United States and Great Britain sat down to discuss where to set the U.S.-Canadian border. The two countries agreed on the 49th parallel but were still uncertain about what to do with the Oregon Territory. Instead of dividing the territory into two pieces, the U.S. and Great Britain agreed to continue to occupy the area together for 10 years before bringing up the discussion again. In 1827, they revisited the topic but decided to put off negotiations on the Oregon Territory yet again.

By the late 1830s and 1840s, the debate over the Oregon Territory came to a head. Countless Americans followed the Oregon Trail out west in search of opportunity. At the same time, many Americans embraced the concept of Manifest Destiny, the idea that the United States was destined to stretch across North America from the Atlantic Ocean to the Pacific Ocean. President James K. Polk was a firm believer in Manifest Destiny and decided to reopen discussions about the Oregon Territory.

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