Conversation so far:
What did David Thompson (explorer) do during his later years?
David Thompson retired with a generous pension from the North West Company.
Did David Thompson (explorer) have any other achievements?
David Thompson's 1814 map, his greatest achievement, was so accurate that 100 years later it was still the basis for many of the maps issued by the Canadian government.

Question: What else is notable about this time?
Self-contained rewrite: What else is notable about David Thompson (explorer) in his later years?