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1. William Clark had sighed with relief after reaching Travelers' Rest on June 30, 1806, "leaving those tremendious mountanes behind us—in passing of which we have experiensed Cold and hunger of which I shall ever remember." Forty-seven years later, in September of 1853, Lieutenant John Mullan, on assignment from the commander of the Railroad Survey expedition, made it from the mouth of Lolo Creek to the Nez Perce Indian village on the Clearwater near today's Kamiah, Idaho, in just nine days. "The route had been represented to me by some to be very rugged and difficult, and by others as feasible and practicable." His conclusion was unequivocal: "the route is thoroughly and utterly impracticable for a railroad route."
From the head of Lo-Lo's fork [of the Bitterroot River] to the Clearwater the country is one immense bed of rugged, difficult, pine-clad mountains, that can never be converted to any purpose for the use of man. . . . I have never met with a more uninviting or rugged bed of mountains.
2. On June 20th of 1806, reflecting on the alternative to retracing their steps across the northern Nez Perce trail, Meriwether Lewis recalled:
From the information of the Chopunnish [Nez Perce] there is a passage which at this season of the year is not obstructed by snow, though the round [route?] is very distant and would require at least a month in its performance. The Shoshones informed us when we first met with them that there was a passage across the mountains in that quarter, but represented the difficulties arising from steep, high and rugged mountains, and also an extensive and barren plain which was to be passed without game, as infinitely more difficult than the route by which we came.
A. W. Tinkham, a civil engineer with Isaac Stevens's railroad explorations and surveys, traveled the so-called southern Nez Perce trail between November 21 and December 24, 1853, proved that it was not a practicable route for a railroad, and confirmed the reports Lewis and Clark had gotten from Indian informants.