Objective: Students will be able to analyze the Lewis & Clark expedition from
an analytical perspective, with regard to time and distance.
Time: 1 or more class periods
Skills: Problem solving, basic math calculations
Content: Science, Math
Throughout their journey, Lewis and Clark had to make careful calculations about the
distances that they had to travel and the projected time that it would take them to reach
their various destinations. In preparing for the expedition, Lewis had to make important
decisions about the number and types of boats to bring along the journey. Since so few
settlers had traveled west of the Continental Divide, much of Lewis's job was pure speculation.
Yet the lives of the Corps members depended upon the accuracy of his and Clark's pre-
dictions, since their calculations determined the nature and amount of provisions the Corps
would carry.
Lewis chose several different boats for the Corps of Discovery's expedition: a specially
designed keelboat, canoes (pirogues-Lewis used these names interchangeably), and an
iron-frame boat that Lewis and Jefferson had dreamed up prior to the voyage and whose frame
Lewis had had constructed in Pittsburgh. The keelboat designed for the Corps was 55 feet long,
8 feet wide at the midpoint, with a 32-foot high mast that could be lowered. The boat could be
propelled four ways: rowing, sailing, pushing, and pulling. Given all of the obstacles in the
Missouri, this flexibility often came in handy. The iron-frame boat, which members of the Corps
dubbed the "Experiment," was a collapsible structure that Lewis envisioned covering with leather
and waterproofing on the overland portion of the Corps's journey between the Missouri and
Columbia Rivers. The iron-frame boat, however, was a disaster. The stitching gaped and the
waterproofing proved inadequate. When Lewis attempted to launch the boat, he claimed that it
"leaked in such manner that she would not answer." Despite these difficulties, Lewis's idea was
a sound one-he knew that the Corps would be in need of new boats following their journey
over land, and he wanted to find something very light to carry. (You may want to link to these web sites:
www.kcmuseum.com/riv4.html; and www.steamercolumbia.org/imagegallery.html; for additional
information on steamboats, see www.steamboats.org or www.sshsa.org)
In addition to the difficulty of predicting what kinds of boats would be most useful on the
expedition, Lewis and Clark also faced the obstacle of the river itself. Much depended upon the
ever-fluctuating flow of the Missouri-a problem that continued to plague travelers on the river
well into the twentieth century. The introduction of the steamboat, with its flat bottom and
light construction, on the Missouri in 1819 helped alleviate some of the problems, but the vagaries
of the river continued to make travel difficult. In the twentieth century, engineers decided to
take matters into their own hands, creating a deep-water channel along the river in order to make
transportation quicker and more reliable.
Aside from the choice of boats for the expedition, Lewis and Clark also had to make sure that they
were traveling along the right path-not an easy task, considering that they were travelling through
territory that few Europeans had ever seen. At one particular juncture near the mouth of the
Missouri River, where the river divided, Lewis and Clark had to make a crucial decision about which
path to follow. One fork, that on the right or north side, ran almost directly east-west, meaning
that the Corps, in following it, would be heading straight toward the mountains. The other fork,
that on the left or south side, reached the Missouri from the southwest and had a swifter current,
but was shallower. By all appearances, the fork on the right seemed more characteristic of the
Missouri the Corps had seen so far-its waters were turbulent and heavy with sediment. For these
reasons, all the other members of the Corps were convinced that the north fork was the true Missouri,
but Lewis and Clark were not so sure. Lewis reasoned that the clearer water of the southern river
perhaps indicated that it descended directly from the mountains. The two captains decided that
each of them would take an exploratory party up the river a ways to see if they spotted any sign
of the Great Falls that allegedly formed the mouth of the river. Based on their observations and
on their examination of the maps, Lewis and Clark decided-against the warnings of the other Corps
members-that the south fork was the true Missouri. Less than a week later, upon the Corps's
arrival at the Great Falls, the decision made by Lewis and Clark to follow the south fork proved
right.
Word Problems
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By Clark's estimation, the Corps of Discovery traveled 4,142 miles one-way, from Wood River,
Illinois to Ft. Clatsop, Oregon. Knowing that the expedition lasted roughly 864 days (round trip),
from May 14, 1804 to September 23, 1806, and assuming that the Corps traveled roughly the same
distance on its return trip, how many miles did the Corps average per day? Assuming that the Corps
spent about 5 hours a day moving forward, and that they were able to travel on 680 of the 864 days
of their expedition, what was their average speed?
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While tracing the Missouri River, the Corps of Discovery often split into two groups. Assume
that one group traveled by foot, led by Lewis at a constant speed of 2 miles per hour, and the other
by boat, led by Clark at the constant speed of 3.5 miles per hour. If the group decided to cover
21 miles of territory on a given day, and they left at the same time, how long would Clark have to
wait for the group led by Lewis? If 75 years later, a steamboat could travel at 5.25 miles per hour,
how much time would be saved in traveling the same distance, as compared to the older boat?
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Had Lewis and Clark taken the northern fork at the junction below Great Falls, they would have
traveled up the Marias River and been off their course toward the Columbia River. Suppose the Corps
traveled along the Marias for fifty miles before realizing their error. If they then turned due
south and traveled 30 miles in a straight line back to the point where their original path would have
put them, how many additional miles would they have traveled than if they had remained on course?
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Lewis and Clark reached a turning point similar to the one described above on April, 1805, at the
junction of the Yellowstone and Missouri Rivers. Had Lewis and Clark listened to their Hidatsa
Indian guides, they could have followed the Yellowstone for a more direct route to the Three Forks.
Instead, following Jefferson's orders to follow the Missouri to its head, the Corps remained on the
Missouri and arrived at Three Forks 13 days later than they otherwise would have. Using the speed
calculated in problem #1, determine how many additional miles they traveled to reach their
destination.
Extended Activities
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Have students do research on each of the ships used by the Lewis and Clark expedition and create
a timeline showing their use over time. In labeling their timelines, have students also indicate
what other historical events/milestones coincided with changes in river transportation. The
following are several good websites to start with: http://www.kcmuseum.com/riv4.html; on steamboats,
www.steamboats.org or http://www.geocities.com/BourbonStreet/Square/6886/photos/deltaqueen2.jpg.
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If your school has its own wood shop, have students try to design and build their own boats for the
Missouri River of 1804. Remind them to consider the river's variable terrain in designing their
boats and to design a boat that can fulfill whatever transportation needs they determine are
important. You may wish to have students read Stephen Ambrose's description of Lewis's attempt
to construct his iron-frame boat and discuss the reasons for his boat's failure. See Stephen E.
Ambrose, Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West,
pages: 244-249.
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