Mackenzie, Alexander.
Voyages from Montreal, on the River St. Laurence, through the Continent of North America, to the Frozen and Pacific oceans, in the Years 1789 and 1793 with a Preliminary Account of the Rise, Progress, and Present State of the Fur Trade of that Country.
New York: Printed and Sold by G.F. Hopkins…1802.

The Englishman Alexander Mackenzie was the first European to cross the Rocky Mountains, and his descriptions of the northwest in Voyages have been noted for their accuracy. On reading them Thomas Jefferson was moved to make plans for an American exploration of the west, which eventually resulted in the expedition of Lewis and Clark.