USA HISTORY

Detailed explanation-1: -Originally Spain, Great Britain, Russia, and the United States claimed the territory. In 1819, under terms of the Transcontinental Treaty, Spain ceded its claims to the territory to the United States.

Detailed explanation-2: -Originally claimed by several countries (see Oregon Country), the region was divided between the UK and the US in 1846. When established, the territory encompassed an area that included the current states of Oregon, Washington, and Idaho, as well as parts of Wyoming and Montana.

Detailed explanation-3: -In 1846 the Oregon Treaty was signed between the US and Britain to settle the boundary dispute. The British gained the land north of the 49th parallel, including the Vancouver Island and the United States received the territory south of the parallel.

Detailed explanation-4: -This area was called the Oregon Territory by the Americans and the Columbia region by the British. The Convention of 1818 resolved some territorial disputes stemming from the War of 1812 and earlier, and resulted in an agreement for both nations to jointly occupy and administer the territory for a period of 10 years.

Detailed explanation-5: -In June 1846, the Senate, preoccupied with war against Mexico, quickly approved the Oregon Treaty with Britain, setting the boundary at the 49th parallel.