On August 12, 1805, the Lewis and Clark Expedition crossed Lemhi Pass into present-day Idaho, the homeland of Sacajawea (Sacagawea).
    With help from Sacajawea's people, the Corps of Discovery crossed over Lost Trail Pass back into today's Montana, only to face the formidable Bitterroot Mountains of north central Idaho. Rescued from starvation and befriended by the Nez Perce Indians, they recuperated, entrusted their horses to the Nez Perce and continued on their epic journey, in cottonwood canoes, to the Pacific Ocean.

This is Mariwether Lewis

This is William Clark

And this is Idaho!( where they went.)

The dotted lines are the part of  Idaho Lewis and Clark went through.

Http://www.gkschools.org/lc.htm