David Thompson

David Thompson, originally a fur trader for the Hudson Bay Company, became a map maker for the rival North-West Company. With his wife and 14 children, he criss-crossed Western Canada and NW United States, surveying and mapping as they went. His results was so accurate, the map was still being used into the early 20th century. It was re-discovered by J.B. Tyrell in the mid 19th century.