Idaho: Lemhi Pass, Tendoy

Lemhi Pass was the highest point reached by Meriwether Lewis and William Clark on their epic journey across the American West. At this mountainous site, the Corps of Discovery first glimpsed the headwaters of the Columbia River and realized that a water passage across the continent was impossible.

Site Office

Beaverhead-Deerlodge National Forest

420 Barrett Street

Dillon, MT 59725

ph.: (406) 683-3900

Web site:

Rising 7,373 feet above sea level on the Continental Divide, lofty Lemhi Pass formed during the last Ice Age as a pair of alpine glaciers scoured in opposite directions, leaving a steep ridge between them. Long before the arrival of Lewis and Clark, Native Americans made use of this route through the otherwise impassable Beaverhead Mountains in the Bitterroot Range. Lemhi Pass anchored a well-worn American Indian trail across the Continental Divide: east for buffalo hunting along the headwaters of the Missouri River and west for the abundant salmon in the Salmon River and its tributaries. For the Shoshone and Nez Perce, the route was especially important for seasonal migrations between hunting areas, and the Blackfoot frequented the trail and pass so often that it was locally known as the “Blackfoot Road.”

Lewis and Clark

Standing on the pass the morning of August 12, 1805, Meriwether Lewis and three expedition members became the first European Americans to cross the Continental Divide south of Alberta and north of New Mexico. Lemhi Pass and the divide formed the western boundary of the Louisiana Purchase and, until 1846, the far northwestern edge of the United States. As the explorers gazed at a seemingly endless sea of rugged mountains and deep valleys to the west, they also realized that the dream of Thomas Jefferson and so many others of a Northwest Passage–a water-only route across the continent–was impossible; there was no easy connection between the Missouri and Columbia Rivers, only a long and grueling overland portage.

Captain Lewis recorded the moment in his journal: “We proceeded on to the top of the dividing ridge from which I discovered immence ranges of high mountains still to the West of us with their tops partially covered with snow.” He descended the pass about three-fourths of a mile, which was much steeper here than on the opposite side, “to a handsome bold running Creek of cold Clear water. here I first tasted the water of the great Columbia river.”

Later, upon returning to his tepee, Lewis received from a warrior a piece of roasted salmon, “which I eat with a very good relish. this was the first salmon I had seen and perfectly convinced me that we were on the waters of the Pacific Ocean.” Despite the arduous task ahead of them, the corps was also elated by the knowledge that they could now trade for the fine Shoshone horses to assist in the portage. The expedition crossed Lemhi Pass numerous times before deeming the Salmon River route too rugged and striking out for their eventual successful crossing of the mountains of Idaho via Lolo Pass, 130 miles to the north.

The intrepid Indian guide for the corps, Sacagawea, was born west of the pass near Tendoy, Idaho. Sacagawea, a Lemhi Shoshone, was kidnapped as an eleven-year-old girl and later sold to a French fur trapper, Toussaint Charbonneau, who enlisted in the Corps of Discovery. Her knowledge of the area’s geography and native residents was invaluable to the expedition. Sacagawea Memorial Camp–a small picnic area about two-tenths of a mile below and to the south of Lemhi Pass–was designated a special recreation area in 1932 and honors the memory of the expedition’s incomparable young guide. A small spring bubbles near the picnic area, the spot where Meriwether Lewis may have paused for a drink on his ascent of the pass on August 12, 1805.

After Lewis and Clark

In the wake of Lewis and Clark, exploration and settlement pushed ever westward. Fur traders made use of Lemhi Pass as they traveled and trapped beaver along the plentiful streams and rivers of the northern Rockies. To them it was “North Pass,” as distinguished from South Pass in Wyoming. In the 1860’s, the region was seized by a gold rush. Freight wagon haulers and a stage line traversed Lemhi Pass during the area’s mining boom. The Red Rock Stage Line connected Salmon City, Idaho, to Red Rock, Montana, the closest railhead in the region. For fifty years the wagons climbed and descended the precipitous pass until 1910, when they were replaced by the Gilmore and Pittsburgh Railroad over Bannock Pass, fifteen miles southeast of Lemhi Pass. The rutted and muddy route never regained its importance, and consequently remains largely as it was in 1805 when Lewis crossed it. Lemhi Pass is among the most pristine segments to be visited along Lewis and Clark’s entire four thousand-mile route.

Just west of the pass in the Lemhi Valley, two small pioneer settlements were founded a few miles apart: Tendoy and Lemhi, Idaho. Both owe their names to a fierce, charismatic, and famous Indian chief, Tendoy. Born near Boise, Idaho, in 1834 of a Bannock father and a Shoshone (Sheepeater) mother, Tendoy distinguished himself in battle against bellicose neighboring tribes. Upon moving to the Lemhi Valley in 1863, he assumed leadership of the Lemhi band. Farsighted and realistic, Chief Tendoy realized the inevitability of European American settlement and guided the Lemhi through a series of treaties, failed agreements, forced relocation, and the establishment of a Lemhi reservation. Throughout, he skillfully negotiated and protected his people’s interests. He died in May, 1907, received a hero’s funeral, and is buried near Tendoy, Idaho.

For Further Information

  • Ambrose, Stephen E. Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West. New York: Simon & Schuster, 1996. Traces the epic Lewis and Clark journey of discovery across the American West to the Pacific and back.
  • Conley, Cort. Idaho for the Curious. Cambridge, Idaho: Backeddy Books, 1982. A comprehensive guide to Idaho’s human and natural geography, particularly detailing the state’s historical development.
  • Crowder, David L. Tendoy, Chief of the Lemhis. Caldwell, Idaho: Caxton Printers, 1969. A thorough autobiography of the famed Shoshone-Bannock Native American Chief.
  • National Forest Service. Lemhi Pass National Historic Landmark. Informative Web site includes map, photographs, road conditions, campground locations, weather information, and phone numbers.