i think this may help you 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. Shortly thereafter the United States contested a unilateral Russian move to grant its citizens a fishing, whaling, and commercial monopoly from the Bering Straits to the 51st parallel. In 1823 President Monroe promulgated his doctrine, which put Russia on notice that the United States did not accept Russian attempts at monopoly. The U.S. claim was based on the explorations of Lewis and Clark and on the establishment of trading posts set up by John Jacob Astor’s Pacific Fur Company, such as Astoria at the mouth of the Columbia River. Great Britain based its claim, in part, on James Cook’s exploration of the Columbia River
