Thompson's main contribution to the development of the Pacific Northwest was to...

David Thompson (30 April 1770 – 10 February 1857) was a British-Canadian fur trader, surveyor, and cartographer, known to some native peoples as Koo-Koo-Sint or "the Stargazer". Over Thompson's career, he traveled some 90,000 kilometres (56,000 mi) across North America, mapping 4.9 million square kilometres (1.9 million square miles) of North America along the way.[1] For this historic feat, Thompson has been described as the "greatest practical land geographer that the world has produced".[2]:xx

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it further strained relations between the north and the south and convinced