The main objective of the Lewis and Clark expedition in 1804 was to explore the newly acquired Louisiana Territory and seek a water route to the Pacific Ocean. Commissioned by President Thomas Jefferson, the expedition aimed to map the land, study its resources, and establish relations with Native American tribes. Led by Meriwether Lewis and William Clark, they traveled over 8,000 miles, documenting flora, fauna, and geography along the way. Their discoveries greatly contributed to American knowledge of the West and facilitated subsequent westward expansion.