From Envisaging The West website:
"Using GIS (Geographic Information Services) software, seven maps that shaped Thomas Jefferson's conceptions of the West have been transcribed and entered into databases, making them interactive. These processes link locations referenced in Envisaging the West's documents to corresponding points on the maps."
1755 | Map
John Mitchell. A map of the British and French dominions in North America, with the roads, distances, limits, and extent of the settlements, 1755 (1st impression of first ed.)View Image | View Interactive Map
Library of Congress, Geography and Map Division.