Meriwether Lewis and William Clark led the famous expedition that explored the western United States, known as the Lewis and Clark Expedition. Commissioned by President Thomas Jefferson following the Louisiana Purchase, the journey commenced in 1804 to gather scientific knowledge, map the territory, and establish trade relations with Native American tribes. Spanning more than two years, the expedition provided valuable insights into the geography, flora, fauna, and indigenous peoples of the western frontier. Their discoveries paved the way for westward expansion and significantly contributed to the understanding of America's vast landscapes during the early 19th century.