The Oregon Treaty was signed between the United States and Great Britain, marking a significant diplomatic resolution to the territorial disputes that arose over the Oregon Territory. This region had been a subject of contention since both powers claimed rights to it, underpinned by the 'Oregon Trail' and the westward expansion that characterized the era. Preceding treaties, including the Treaty of 1818, had only partially settled the issue, providing for joint occupation but leaving the borders ambiguous. The negotiation culminated after a series of discussions led by American diplomat James Buchanan and British Foreign Secretary Lord Aberdeen.

The treaty established the 49th parallel as the border from the Rocky Mountains to the Pacific Ocean, allowing for American control of the Oregon Territory, which included present-day Oregon, Washington, Idaho, and parts of Montana and Wyoming. This was a strategic gain for the U.S., opening up the western frontier for settlement and further economic development. The agreement was set against a backdrop of rising nationalism in the U.S. and the belief in Manifest Destiny—which held that Americans were destined to expand across the continent.

Additionally, the treaty provided for the peaceful resolution of border disputes and reflected the growing necessity for both nations to avoid military conflict. By clearly demarcating their territories, the United States and Britain resolved one of the last significant territorial disputes in North America during the nineteenth century, paving the way for increased westward migration by American settlers and furthering the expansion of U.S. influence into the Pacific Northwest.