Final answer:
The Lewis and Clark expedition across the western United States is equivalent to a journey into the unknown. Their purpose was to explore the new land, discover potential trade routes, and gather information on the geography, flora, fauna, and native peoples of the region.
Step-by-step explanation:
The Lewis and Clark expedition across the western United States is today's equivalent of a journey to the unknown. The purpose of the expedition was to explore the newly acquired western lands, discover potential trade routes, and gather information on the geography, flora, fauna, and native peoples of the region. Despite not finding the Northwest Passage, Lewis and Clark's expedition greatly contributed to the knowledge and mapping of the territory, solidifying the United States' claim to the immense land.