Since the region opened to European exploration in the 18th century, the northwest corner of North America had been the subject of rival territorial claims by Russia, Spain, Great Britain and the United States. Disputes arose over fishing and navigation rights and over the exploitation of the increasingly important fur trade. In 1819 the United States and Spain signed the Adams–Onís or ‘Transcontinental’ Treaty, under which Spain ceded the state of Florida to the US and, in return for a $5million-settlement, established their mutual borders in Texas and in the Rocky Mountains. Two years later the retrenching Spanish granted Mexico its independence. In treaties in 1824 and 1825 the Russians ceded their claims south of the 54°40′ parallel to the US and agreed reciprocal trading and navigation rights with the British. However, the border between the United States and the British colony that was to become Canada were disputed, with the Americans claiming all the territory up to the 54°40′ parallel and the British claiming all the territory (‘British Columbia’) down to the 42nd parallel. The Oregon Treaty of 1846 between Britain and the US settled on a compromise that limited the US (Oregon State) boundary at the 49th parallel, with a nautical deviation that preserved Britain’s control of strategic Vancouver Island. Further disputes ensued concerning navigation rights and the status of nearby islands, but the vexed issue of the US northwest border was at last resolved.
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