The Lewis and Clark expedition was commissioned by Thomas Jefferson to explore and map the newly purchased Louisiana Territory, to identify a practical route to the Pacific Ocean, and to learn more about the native peoples who lived in the region. Headed by Captain Meriwether Lewis and Second Lieutenant William Clark, the Corps of Discovery Expedition took place from May 1804 to September 1806. Lewis and Clark and the rest of the exploration party were the first Americans to travel through what became the western United States. The expedition included a Shoshone woman named Sacagawea who served as a translator, guide, and diplomat to the many native tribes they encountered. Jefferson was also interested in the flora and fauna of the European-untraveled West, and had hundreds of specimens sent back to Virginia during the two-year undertaking. This collection of images, letters, and maps provides information about the expedition leaders, the president that made the expedition possible, and the people they encountered along the way.