<P> David Thompson ( 30 April 1770 -- 10 February 1857 ) was a British - Canadian fur trader , surveyor , and map - maker , known to some native peoples as Koo - Koo - Sint or `` the Stargazer . '' Over Thompson 's career , he travelled 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 . For this historic feat , Thompson has been described as the `` greatest land geographer who ever lived . '' </P>
who was the explorer who opened up the fur trade route to the great lakes
David Thompson