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Historical Background

Planning the eastbound trek

Hard put though Lewis and Clark were to keep their charges occupied during the long and dreary winter, they managed to keep busy themselves. Lewis made fresh comments in his journals on botanical, zoological, meteorological, and anthropological topics involved on the journey so far and also systematized and expanded observations he had made since leaving the Mandan villages. Clark codified his geographical data and worked on a series of master maps, including one from Fort Mandan to the Pacific coast, as well as various detail maps of specific areas west of the Great Falls of the Missouri.

As they reviewed their track across the continent and poured over their notes and maps, Lewis and Clark were satisfied that the route they had followed was the best possible with one clear exception: failure to utilize the overland shortcut connecting Travelers Rest and the area west of the Great Falls that the Minitaris, Old Toby, other Shoshonis, and the Nez Perces had told them about. [126] The land-water route they had employed, via the Three Forks, Lemhi Pass, and the Lemhi-Salmon-Bitterroot Rivers, was not only needlessly long, 500 or 600 miles farther than the shortcut the captains calculated, but was also more difficult because of severe navigational problems on the Missouri above the Great Falls, especially the headwaters.

To accomplish various exploratory objectives on the eastbound journey, particularly reconnaissance of the Upper Marias and Yellowstone, Lewis and Clark decided to split the expedition into two groups at Travelers Rest in the Bitterroot Valley, the eastern terminus of the Lolo Trail. One segment, led by Lewis, would follow and investigate the shortcut eastward to the Great Falls area. Then it would probe the Upper Marias to determine for Jefferson how far north it extended.

The other group, under Clark, would move southeastward from Travelers Rest and pick up the canoes and supplies cached at Camp Fortunate. From there, it would proceed to the Three Forks of the Missouri, from which a small boat party would travel to the Great Falls to rendezvous with a detachment of the Lewis contingent and make the portage. The bulk of the Clark complement would move overland to the Yellowstone River and explore it to its mouth, as Lewis had promised Jefferson in a letter before they had left Fort Mandan the previous spring. The two groups planned to reunite at the mouth of the Yellowstone.

Readying to depart

As winter neared an end, everyone grew restless to head home. Lewis and Clark had a special reason for wanting to make an early start—a desire to cross the Lolo Trail with the Nez Perces as soon as the deep snow subsided. The commanders were anxious to make all possible speed in reaching their villages, where they had left their horses. The chiefs had told them the previous autumn that they intended to cross to the eastern side of the mountains as soon as possible in the spring. The two captains were afraid that if the Indians did so before their arrival they would be unable to reclaim their mounts and would have difficulty in making the recrossing on their own.

A tentative departure date from Fort Clatsop of April 1 was established. Shields checked and put all the guns in order, and other preparations were carried out. One of the final acts was the writing of notices that listed the members of the expedition and briefly explained its purpose and accomplishments. Included on the back of several of them was a sketch map showing the Upper Missouri and Columbia drainage systems and delineating the group's outbound and proposed eastbound routes. The notices were given to several chiefs and one was posted in the captains' room at Fort Clatsop. It was thought that some of them might find their way into the hands of northwest traders and would constitute a record of the expedition in the event of a catastrophe on the way home. [127]