David Thompson reaches the mouth of the Saskatchewan River in Manitoba.
The Saskatchewan River (Cree: kisiskciwani-spiy, "swift flowing river") is a major river in Canada, about 550 kilometres (340 mi) long, flowing roughly eastward across Saskatchewan and Manitoba to empty into Lake Winnipeg. Through its tributaries the North Saskatchewan and South Saskatchewan, its watershed encompasses much of the prairie regions of central Canada, stretching westward to the Rocky Mountains in Alberta and north-western Montana in the United States. It reaches 1,939 kilometres (1,205 mi) to its farthest headwaters on the Bow River, a tributary of the South Saskatchewan in Alberta.
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 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 practical land geographer that the world has produced".: xxxii