History Resources

A map of the Louisiana Territory, 1806

A Spotlight on a Primary Source by Meriwether Lewis

A Map of the Louisiana Territory, 1814. (Gilder Lehrman Collection) The 1803 Louisiana Purchase from France during Thomas Jefferson’s first term as president more than doubled the size of the United States. Jefferson’s next step was to learn all about this new territory of the United States. He chose Meriwether Lewis, a former army captain and his own private secretary, to lead the expedition. Lewis chose another army captain, William Clark, to join him and put together the team. Clark’s exceptional mapmaking skills proved invaluable, and he kept detailed records throughout the journey.

They left St. Louis, Missouri, in May 1804 and reached the Pacific Ocean near what would become Columbia, Oregon, in November 1805. Their primary tasks were to survey the new lands west of the Mississippi River and to locate a water route to the Pacific. They kept meticulous journals about plant and animal life, rocks and minerals, weather conditions, and a wide variety of other details about this new territory.

Another important goal was to initiate good relationships with the American Indians. During the winter, a French Canadian trader, Toussaint Charbonneau, and his wife, Sacagawea, a Shoshone Indian, joined the expedition. Sacagawea was instrumental in introducing Lewis and Clark to Native Americans. She acted as a translator and presented the expedition as peaceful.

The expedition returned to Missouri in September 1806 with valuable maps. After Lewis’s death in 1809, Clark took responsibility for organizing and releasing the expedition journals to eager scientists and curious Americans.

Questions for Discussion

Read the document introduction and closely examine the enlarged document image in order to answer these questions. A current physical and political map of the United States will help students as well.

  1. Use specific information on the Lewis and Clark map to locate the area they explored on a current map of the United States. Identify the region depicted by naming current states (whole states or parts of states) in that region.
  2. Why did Lewis and Clark so carefully identify the geography of the region they explored? Identify geographic features by carefully studying their drawing. Which of these features would they have used to their advantage and which might have been a major obstacle to their travels?
  3. Lewis and Clark encountered Native Americans as they journeyed west. Use the information on the map to identify the names of the several tribes they met.
  4. In the Title section of the map at the bottom left, there is a notation that the map was created “By Order of the Executive of the United States.” Who was that person and what was his interest in having this information?
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