Meriwether Lewis crossed the Continental Divide at Lemhi Pass on August 12, 1805, during the Lewis and Clark Expedition.
Lemhi Pass lies in the Beaverhead Mountains of the Rocky Mountains, on the modern border between Idaho and Montana. Lewis crossed it with three other expedition members while searching for a practical route west through the newly acquired Louisiana Purchase.
The pass did not lead directly to an easy water route. Instead, the expedition encountered more rugged mountains beyond it and continued its journey with assistance from Shoshone people. The entire expedition crossed Lemhi Pass on August 26, 1805, before continuing toward the Pacific coast.
Lemhi Pass is sometimes confused with Lolo Pass. Lolo Pass was used later during the expedition’s westward route through the Bitterroot Mountains, while Lemhi Pass was the point where Lewis first crossed the Continental Divide. The pass was designated a National Historic Landmark in 1960.