In 1803, the United States doubled in size at the stroke of a pen. The Louisiana Purchase Treaty, which was signed in April of that year and ratified by the Senate in October, transferred hundreds of millions of acres of land west of the Mississippi River from France to the U.S. for a few cents per acre. This acquisition opened up new opportunities for westward expansion by the U.S. It also began a period of dramatic transformation, both for the United States and for the indigenous communities already living in the Louisiana territory.
The Louisiana Purchase spurred a number of attempts to explore the features and boundaries of the territory. The best known of these journeys of exploration was the Lewis and Clark expedition, which began in 1804 and lasted more than two years. Lewis and Clark's Corps of Discovery traveled from the Missouri River to the Pacific Ocean and back on a quest to connect the eastern U.S. with the west via a water passage, documenting the people, terrain, and resources that they encountered there.
Highlights from the Louisiana Purchase and the Lewis and Clark expedition
October 1, 1800: French leader Napoleon Bonaparte acquires the vast Louisiana Territory from Spain in a secret agreement.
January 11, 1803: President Thomas Jefferson nominates Robert Livingston and James Monroe to serve as envoys to France “for the purpose of enlarging, and more effectually securing, our rights and interests in the river Mississippi, and in the territories eastward thereof.”
April 1803: Napoleon offers to sell the entire territory of Louisiana to the U.S.
April 30, 1803: The Louisiana Purchase Treaty is signed by Livingston and Monroe.
October 20, 1803: The Senate ratifies the Louisiana Purchase Treaty.
June 1803: Thomas Jefferson sends a letter of instructions to his secretary, Meriwether Lewis, appointing Lewis to lead an expedition to explore the American west. Lewis would later choose William Clark as co-leader of the group.
May 1804: Lewis and Clark’s Corps of Discovery begins their expedition near St. Louis, Missouri.
April 1805: Sacagawea, a Shoshone woman, joins Lewis and Clark’s expedition as a guide and interpreter as the group leaves its winter camp on the Missouri River.
November 1805: The expedition reaches the Pacific Ocean.
September 1806: The Lewis and Clark expedition ends as the explorers return to St. Louis.
April 1904: The Louisiana Purchase Exposition, also known as the St. Louis World’s Fair, opens its gates.
May 1968: The 630-foot Gateway Arch is dedicated as the centerpiece of the Jefferson National Expansion Memorial in St. Louis.
Suggestions for Teachers
Ask students to read one or more items from the time of the Louisiana Purchase and identify arguments in favor of the purchase and opposing it. Then, ask students to use more recent primary or secondary sources to evaluate those arguments.
The set includes several maps, some embedded with other information. Ask students to arrange the maps in chronological order and then to evaluate how each reflects what was known at the time. Ask them to consider, thinking about all of the maps: What changed over time? What stayed the same?
Assign or ask students to select an item related to the planning of the Lewis and Clark expedition. What problems or events did the planners anticipate? Encourage students to investigate secondary accounts of the expedition to identify which problems did or did not in fact emerge, and which problems the planners did not anticipate.
Direct students to select an item that depicts or describes events from the Lewis and Clark expedition. Encourage them to identify the different perspectives that are included in the account. Who are the central figures of this depiction? Are any perspectives missing?
Ask students to select a newspaper article or other item from the 20th century that commemorates the Louisiana Purchase or Lewis and Clark expedition. Invite them to explore how perceptions of these events have changed over the intervening centuries. How is the language they use to describe these events the same or different from the ways in which they were described nearer the time they took place? How is it different from the ways in which these events would be described today? How can they explain these changes in perception? For a more in-depth study of perception and perspective, students might read the “About” page linked to each newspaper.