According to the book Mysterious Monsters written by authors Daniel Farson, and Angus Hall the first recorded sighting of a Sasquatch track by a non-Native in North America occurred in what is now Jasper, Alberta, in 1811.
"While crossing the Rockies in an attempt to reach the Columbia River, the explorer and trader David Thompson came across a set of strange footprints measuring 14 inches long by 8 inches wide. Four toe marks were shown in the deep snow. This was unlike the five-toe print of a bear, and convinced those who heard of the track that it did not belong to a grizzly."
In more modern times similar tracks have been found in British Columbia, Alberta, Manitoba, Ontario, and Quebec as well as throughout the United States Of America.
Sources: Mysterious Monsters by Daniel Farson, and Angus Hall ISBN: I 85471 040 0