Experts disagree on the exact route Lewis and Clark took over this divide, and no one knows where they camped on the cold, snowy night of September 3, 1805, after struggling up the trackless North Fork of the Salmon River. John Ordway wrote that on Tuesday, 3rd Sept. 1805, the party went up and down rough rocky mountains all day, some horses fell backwards and rolled to the bottom, in some places they had to cut a road through thickets, several small showers of rain fell, and they lay down wet, hungry, and cold after much fatigue and 11 miles that day. Why they ventured into some of the most rugged country of their journey instead of taking one of the established Indians trails east of here remains uncertain; early fall weather, reluctance to backtrack, Clark's determination to continue on the most direct route, or ignoring the advice of the Shoshoni Indians and their guide Old Toby are all possible explanations. People have lived and traveled in this wild, rugged land for 10,000 years, yet the Salish and other tribes rarely ventured over Lost Trail Pass. For centuries, the pass over the continental divide now known as Gibbons Pass was the primary travel route for both Indians and settlers, but it lost its importance in the 1930s when US Highway 93 was carved out of the mountains over Lost Trail Pass. The Alta Pine, the oldest known Ponderosa Pine on the Bitterroot National Forest, was 905 years old when it died in 1991; native people had been crossing these mountains for more than 9,000 years before it took root, and the tree was 700 years old before the first horse traveled beneath its limbs.