Lewis and Clark Journals, Great Falls of the Missouri River

An 1805 map from the Lewis and Clark expedition showing the geography of the Great Falls Portage of the Missouri River

Historical Period

Expansion, Slavery, and Calls to Reform

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12 Analysis questions 9 Vocabulary Words

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About

This map of the northern portion of the Missouri River was hand-drawn in 1805 by an explorer of the western lands of North America. Following the U.S. acquisition of the Louisiana Territory, President Thomas Jefferson wanted to find out about the landforms, waterways, plants, and animals. He also wanted to know what resources were available west of the Mississippi that could be exploited for economic gains through trading, mining, logging, and other means. Finding out about the Indigenous people who lived in the area was crucial too. Since this was also a military expedition, Jefferson wanted an assessment of the military threat posed by Indigenous communities to westward expansion. In 1803, Jefferson commissioned Meriwether Lewis and William Clark to form an expedition to do just this. Starting from St. Louis, Missouri, and ending at the Pacific Ocean uncovered much information, which they recorded in journals that contained notes, illustrations, and detailed maps. The route shown on this map, known as the Great Falls Portage, was dangerous. It took the Corps of Discovery 31 days to travel just 18 miles.

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Lewis and Clark Journals, Great Falls of the Missouri River

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Analysis Questions

Foster inquiry and understanding with these source-specific questions, designed to be accessible even for those with limited background knowledge.

say hello to the source

1

Without closely examining this map from 1805, what do you notice about it?
2

Look at the title of the map. “Draught” is a British word meaning the depth of water needed for a boat to float. “Portage” refers to the carrying of boats and their cargo over land between two bodies of water. Based on this and a glance at the map itself, what do you think the map shows?

make observations

3

What can you tell about the Missouri River from this map?
4

A tributary is a river or stream that flows into a larger body of water. What tributaries of the Missouri River have the mapmaker shown on the map?
5

Which physical feature does the mapmaker identify near the Portage River?
6

Rapids are a fast-moving part of a river or stream. How does the mapmaker represent rapids on the map?

interpret what you see

7

In 1803, the United States acquired the land known as the Louisiana Territory. The U.S. government then selected Meriwether Lewis and William Clark to lead the Corps of Discovery to gather information about the Louisiana Territory. Why would the information on this map be helpful for the U.S. government? What makes you say that?
8

The Corps of Discovery took 31 days to travel the 18 miles shown on the map. Why might their journey have taken so long? What details on the map support your response?
9

The mapmaker did not show the terrain the expedition traveled over to avoid the rapids. Based on what you see on the map, what do you think the terrain was like?

use it as evidence

10

Who do you think created the names of the natural features on the map? Why do you think this? What do you think was their inspiration for the names?
11

How might historians use a map like this today? Why would it be considered a valuable tool?
12

What are some of the limitations of this source?

Vocabulary

Use these related vocabulary terms to build students’ understanding and support more meaningful discussions and learning outcomes in your classroom.

Definition

a steep waterfall or multiple smaller waterfalls

Example

Members of the expedition watched as water poured from the cascade into the pool of water below.

Definition

the expedition led by Meriwether Lewis and William Clark to explore and chart the Louisiana Territory

Example

The Corps of Discovery charted the course of the Missouri River as they traveled from St. Louis to the Pacific Northwest.

Definition

the depth of water needed for a boat to float (British spelling)

Example

The draft of the river was too shallow for the boat to safely travel.

Definition

land bought by the United States from France that stretched from the Mississippi River to the Rocky Mountains and from the Gulf of Mexico to the Canadian border

Example

In 1803, the United States nearly doubled the size of the country by buying the Louisiana Territory from France for $15 million.

Definition

the steepness of a slope

Example

The pitch of the roof was too low, which meant that pools of water formed on top of the house.

Citation & Details

Citations

Creator: Meriwether Lewis
Date Created: April 3, 1806
Materials and Measurements: paper and ink
Point of Origin: Columbia River, Washington
Object Identifier #: Lewis and Clarck Journal Codex K

American Philosophical Society. (2001). Lewis and Clark Journals. https://as.amphilsoc.org/repositories/2/resources/696

Britannica Editors (2004, April 29). Rod. In Britannica.com. Encyclopedia Britannica. https://www.britannica.com/science/rod-measurement

Buckley, J. H. (2026, March 20). Lewis and Clark Expedition. In Britannica.com. Encyclopedia Britannica. https://www.britannica.com/event/Lewis-and-Clark-Expedition

Library of Congress. (n.d.). Jefferson's Secret Message Regarding the Lewis & Clark Expedition: Primary Documents in American History. https://guides.loc.gov/jefferson-secret-message/external-websites

National Park Service. (2021, December 30). Great Falls Portage. https://www.nps.gov/places/great-falls-portage-mt.htm

U.S. Department of State: Office of the Historian. (n.d.). Louisiana Purchase, 1803. https://history.state.gov/milestones/1801-1829/louisiana-purchase