Primary Source Documents

Lewis, Clark, and the Corps of Discovery

By The OE Staff

Subjects: Cartography, Colonialization, Early Exploration, Native Americans, Politics, Western Expansion


Lewis and Clark Expedition, Dr. William Lang

No exploration of the Oregon Country has greater historical significance than the Voyage of Discovery led by Meriwether Lewis and William Clark. Historians and geographers judge the Lewis and Clark Expedition, which brought more than thirty overland travelers into the Columbia River Basin in 1805-1806, as the most successful North American land exploration in U.S. history. Officially called the Corps of Volunteers for North West Discovery, the Expedition was carried out under the auspices of the U.S. Department of War, with presidential and congressional authorization.

The expeditionary force left the Mississippi River Valley in spring 1804, traveling up the Missouri River to the Continental Divide, then down the Snake and Columbia Rivers west to the Pacific Ocean, and returning east on the Columbia, Yellowstone, and Missouri Rivers to St. Louis in September 1806. The explorers traveled more than eight thousand miles, by water and land, in boats, on horseback, and by foot. The journey took just over twenty-eight months, and only one member of the Corps died, the result of disease. They met hundreds of Native people from dozens of groups along the exploration route, mostly under friendly or conciliatory conditions, but not without conflict. They also cataloged hundreds of new plant and animal species unknown to science of the day. The origins and ambitions of the Expedition reached back more than two decades before the explorers crossed the Continental Divide in August 1805; but the nine months the Corps of Discovery spent in Oregon Country left a lasting imprint on the region, while their reports described it for the larger world. [Read the full entry] (

Content Standards

  • 1.17 Explain the use of different kinds of historical sources to study the past.
  • 2.19 Develop and analyze a timeline of events in the history of the local community.
  • 2.20 Generate questions using a historical source as it relates to the local community's history.
  • 3.16 Generate questions using multiple historical sources and examine their validity.
  • 3.17 Use a variety of historical sources including artifacts, pictures and documents to identify factual evidence.
  • 4.7 Explain the interactions between the Pacific Northwest physical systems and human systems, with a focus on Native Americans in that region.
  • 4.8 Compare and contrast varying patterns of settlements in Oregon, considering, past, present, and future trends.
  • 4.9 Identify conflicts involving use of land, natural resources, economic interests, competition for scarce resources, different political views, boundary disputes, and cultural differences within Oregon and between different geographical areas.
  • 4.17 Use primary and secondary sources to explain events in Oregon history.
  • 4.21 Analyze historical accounts related to Oregon to understand cause-and-effect.
  • 4.22 Determine the validity of multiple sources, both historical and current, including but not limited to, diverse, primary and secondary sources.
  • 5.3 Compare and contrast tribal forms of government, British monarchy, and early American colonial governments.
  • 5.5 Describe how national government affects local, state, and Oregon tribal governments.
  • 5.20 Identify and examine the roles that American Indians had in the development of the United States.
  • 5.21 Identify issues related to historical events to recognize power, authority, and governance as it relates to systems of oppression and its impact on ethnic and religious groups and other traditionally marginalized groups in the modern era (bias and injustice, discrimination, stereotypes).
  • 5.22 Summarize how different kinds of historical sources are used to explain events in the past.
  • 5.23 Use primary and secondary sources to formulate historical questions and to examine a historical account about an issue of the time.
  • 5.24 Explain why individuals and groups, including ethnic and religious groups, and traditionally marginalized groups during the same historical period differed in their perspectives of events.
  • 6.18 Evaluate the impact of systems of colonial cultures on the indigenous peoples, such as termination, sovereignty, and treaties.
  • 7.20 Determine and explain the historical context of key people, cultures, products, events, and ideas over time including the examination of different perspectives from indigenous people, ethnic and religious groups and other traditionally marginalized groups throughout the Eastern Hemisphere.
  • 8.3 Compare and contrast how European governments and the United States government interacted with Indigenous peoples.
  • 8.24 Examine the cause and effect of social, political, and economic factors that motivated westward expansion, invasion of indigenous peoples, institutions, and the resulting impacts.
  • 8.29 Use and interpret relevant primary and secondary sources pertaining to U.S. History from multiple perspectives.
  • HS.67 Evaluate historical sources for perspective, limitations, accuracy, and historical context.

Additional Sources

Oregon Encyclopedia Entries

"Lewis and Clark Expedition," by William Lang

"William Clark," by William Lang

"Meriwether Lewis," by William Lang

"Sacagawea," by Stephenie Ambrose Tubbs

"York," by Darrell Millner

"Jean Baptiste Charbonneau," by Albert Furtwangler

"Toussaint Charbonneau," by William Lang

"Patrick Gass," by William Lang

"John Colter," by Jeff LaLande

"Fort Clatsop," by Kelly Cannon-Miller

"Portland basin Chinookan Villages in the early 1800s," by Robert Boyd and Henry Zenk

"Wapato (Wappato) Valley Indians," by Robert Boyd

"Cathlapotle," by Kenneth Ames


Donald Jackson, ed. Letters of the Lewis and Clark Expedition, 2 vols., 2d ed. Urbana: Universityof Illinois Press, 1978.

Gary E. Moulton, ed. An American Epic of Discovery: The Lewis and Clark Journals. Lincoln: University of Nebraska Press, 2003.

James P. Ronda. Jefferson’s West: A Journey with Lewis and Clark. Monticello, VA: Thomas Jefferson Foundation, 2000.

James P. Ronda. Lewis and Clark Among the Indians. Lincoln: University of Nebraska Press, 1984.

Jon Meacham, Thomas Jefferson: The Art of Power. New York: Random House, 2012.

Richard Engeman. “Research Files: The Jefferson Peace Medal: Provenance and the Collections of the Oregon Historical Society.“ Oregon Historical Quarterly (Summer 2006): 290-98.

William L. Lang and Carl Abbott. Two Centuries of Lewis and Clark: Reflections on the Voyage of Discovery. Portland: Oregon Historical Society Press, 2004.

Oregon Public Broadcasting Documentaries

Searching for York

Additional Lesson Plans

The Lewis and Clark Expedition: Digital Public Library of America

Lewis & Clark's Expedition to the Complex West: DocsTeach National Archives


The OE Staff. Lewis, Clark, and the Corps of Discovery. 2021. Retrieved from The Oregon Encyclopedia, (Accessed May 24, 2024.)

Teacher Guide

  1. An important goal of the expedition was mapping the path of journey and noting important geographic information, such as the courses of rivers, location of mountains, and dangerous passages. Closely examine and read about 1. Map of Lewis and Clark's Track How did Lewis and Clark complete this task?

  2. Lewis and Clark encountered many Native Nations during their expedition. Examine and read about the following documents. 2. Estimate of Western Indians, Lewis and Clark Journals 3. Conflict with the Piegans 4. Yelleppit and the Walla Wallas What kind of information about Indian peoples did they record in their Journals? What do we learn about Native peoples and their lives?

  3. The Captains took supplies, guns, medicines, tools, gifts for Indians they met, and much more with them on their journey. Examine and read about the following document and artifacts. 4. Yelleppit and the Walla Wallas 5. Jefferson Peace Medal 6. Captain Meriwether Lewis's Branding Iron How did these items aid the Corps of Discovery in their journey to the Pacific and back?

  4. In their meetings and exchanges with Native peoples, how did Lewis and Clark establish good relations with Indians, and how and why did they create poor relations? Review and consider the following documents and artifacts. 3. Conflict with the Piegans 4. Yelleppit and the Walla Wallas 5. Jefferson Peace Medal 6. Captain Meriwether Lewis's Branding Iron

  5. President Thomas Jefferson, in his instructions to Meriwether Lewis in 1803, emphasized the need for scientific information about the lands, rivers, plants, and animals the Corps observed. How did Lewis and Clark complete this task during the expedition? Use the following documents to draw conclusions about how Lewis and Clark gathered scientific information. 7. Clark's Drawing of a White Salmon Trout 8. Meriwether Lewis to Thomas Jeferson, 1805

  6. The Lewis and Clark Expedition is a famous exploration in American history. How do the following documents inform us how the expedition was remembered by later generations of Americans? 9. Proposed Site for Lewis and & Clark Centennial Exposition 10. Ode to Sacajawea

  7. How was the Lewis & Clark Expedition viewed 100 years later in 1905? Was it viewed as a success? How was the Expedition commemorated two hundred years later in 2005? To find answers, explore “Lewis & Clark: The National Bicentennial Exhibition web site” that hosted a touring exhibition from 2004 to 2006. Or read “A Conversation on the History and Commemoration of the Lewis and Clark Expedition,” with historians William L. Lang and Carl Abbott, Roberta Conner (Umatilla, Cayuse, Nez Perce), director of the Tasmástlikt Cultural Institute, and Christopher Zinn, then director of the Oregon Council for the Humanities.