Based on surveys conducted only a few years after the Treaty of Paris ceded lands east of the Mississippi to England, Lieutenant Ross’s detailed map was a significant advance over such distinguished French cartographers as D’Anville. On a scale like few others for the length of river depicted, the Ross map was widely held to be the most reliable map of the river produced in the 18th century—it clearly evidences the Mississippi Valley’s growing social, political, commercial and agricultural significance.