David Thompson travelled some 90,000 kilometres across North America as a fur trader and surveyor, mapping one-fifth of the continent. His work was so accurate it remained the basis of all maps of the west for almost a century. And yet, he died in obscurity, his remarkable achievements largely forgotten. His biographer D'Arcy Jenish joins me to talk about this remarkable man’s life and work, and his role in creating the Canada we know today.