The main goal of the Lewis and Clark Expedition (1804-1806), commissioned by President Thomas Jefferson, was to explore and map the newly acquired Louisiana Territory and establish an American presence in the West. The expedition aimed to find a water route to the Pacific Ocean, facilitate trade, and strengthen the United States' claim to the region following the Louisiana Purchase in 1803. Meriwether Lewis and William Clark, along with their team, gathered valuable information about the geography, flora, fauna, and indigenous peoples they encountered. This exploration greatly contributed to the westward expansion of the United States and increased scientific and geographic knowledge of the continent.