Map of Lewis and Clark's Journey across the Western Part of America

The 1803 Louisiana Purchase, an incredible deal made with France during Thomas Jefferson’s first term as president, 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. It was Lewis’s job to pick a command partner and assemble the crew he thought would work the best. Lewis chose another army captain, William Clark, to join him and put together the team. Clark’s exceptional map-making 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 task was to survey the new lands west of the Mississippi River, but they also searched for a water route straight through to the Pacific, all the time keeping 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 Native Americans they met on the way. 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 along the way. She could translate, and show that their presence was peaceful.

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