The Lewis and Clark Expedition, which began in 1804, was a pivotal exploration of the western territories of the United States, commissioned by President Thomas Jefferson. Led by Meriwether Lewis and William Clark, the expedition aimed to map the newly acquired lands following the Louisiana Purchase and to find a route to the Pacific Ocean. Their findings greatly expanded knowledge of the geography, biology, and indigenous cultures of the region, influencing westward expansion.

The Lewis and Clark Expedition provided vivid accounts of the American West, which fueled the frontier mythology and nature imagery prevalent in 19th-century poetry. Poets such as Walt Whitman and Emily Dickinson drew inspiration from these explorations, incorporating themes of vast landscapes and the human experience in their works.