Expansion and Manifest Destiny: The Louisiana Purchase of 1803 had dramatically expanded the nation's territory, and Jefferson believed that it was essential to explore and claim these newly acquired lands. The expedition was seen as a way to assert American sovereignty over the region, prevent foreign powers from encroaching, and secure trade opportunities with Native American tribes.
Discovery of a Northwest Passage: There were lingering hopes that a viable Northwest Passage existed, a water route connecting the Atlantic and Pacific Oceans through North America. Jefferson desired to find such a passage, as it would significantly reduce travel time and distance for trade between the East Coast and Asia, potentially opening up lucrative economic opportunities.
Establishing Trade with Native Americans: The expedition aimed to establish trade relations and diplomatic alliances with the various Native American tribes encountered along the journey. Jefferson hoped that these interactions could foster peace and cooperation between the United States and indigenous nations while also opening new markets for American goods.
Gathering Data for Policymaking: The Lewis and Clark expedition was tasked with collecting detailed information about the geography, climate, flora, fauna, and resources of the unexplored regions. This data would be invaluable in forming policies related to land use, resource management, and territorial expansion.