Engineer and author Ted S. Hall talks about the Corps of Discovery’s Lost Trail Descent into Darby from Idaho on September 3, 1805. For many years, the specific route that the explorers followed was unknown until James West Gallogly, an assayer and later forest ranger, discovered the exact path in the late nineteenth century. Hall—who correlates Clark’s hand-drawn map to today’s USG’s quad maps—is assisted by Gallogly’s great-niece, Elisabeth Gallogly Bacon, and fellow engineer Tim Lee connects Gallogly’s finding and Clark’s maps to Google Earth.