Step 3: Which branch to follow?

"To mistake the stream ... and then be obliged to return and take the other stream would not only loose us the whole of this season but would probably so dishearten the party ..." Lewis, summer 1805

ewis and Clark learned much about the western lands and the course of the Missouri River from the Native American tribes and the fur traders and trappers living, working and trading near Fort Mandan, in the Knife River area of present-day North Dakota. Native Americans told the expedition that as they approached the Rockies, the Missouri River would begin to run clear, the result of a series of "great falls" on the river. When the expedition left Fort Mandan in April of 1805, they had a fairly good idea of the geography of the rivers and the mountains they would encounter.

On June 2, the expedition camped opposite the "entrance of a very considerable river" flowing into the Missouri from the north. The two captains were puzzled by the size and the location of this river. They knew of only one major tributary flowing into the Missouri from the north, the "River That Scolds At All Others," which they passed on May 8. What was this river, and more importantly, which fork was the Missouri?

The expedition explored both rivers, measuring their widths, depths and comparative velocities.

The north fork was the deeper of the two, with a current that ran in the same "boiling and roling manner" as the Missouri. The water was a "whitish brown colour very thick and terbid, also characteristic of the Missouri." The bottom was "composed of some gravel but principally mud ... In short, the air and character of this river is so precisely that of the Missouri below ..."

The south fork was "perfectly transparent," with a rapid current and a "smooth unriffled surface." The bottom was covered with "round and flat smooth stones like most rivers issuing from a mountainous country." To the southwest, the expedition could see a "range of high mountains."

The captains called for a meeting. As a member of the expedition, do you think you should:

A. Return to the "River That Scolds At All Others" for further investigation of that river and the countryside around it.
B. Follow the north fork, which so closely resembles the Missouri River you have been traveling for so many months.
C. Take the south fork, which so closely resembles a river that flows from the mountains you can see in the distance.