David Thompson (1770-1857) was a Canadian explorer, cartographer, and surveyor. He was the first white man to descend the Columbia River from its source to its mouth.

David Thompson was born at Westminster, England, on April 30, 1770. After a surprisingly good education at Grey Coat School, a charity school near his home, he was apprenticed to the Hudson's Bay Company at the age of 14. He was sent out immediately and spent the years from 1784 to 1797 as a clerk, either at the bay or at various locations in the interior. He left the company's employ in 1797, in circumstances that virtually amounted to desertion. It was a poor repayment to an employer that had treated him well and trained him as a surveyor.

It was his surveying skill and his wilderness experience which made Thompson welcome at the North West Company, the great rival of the Hudson's Bay Company for the...