Final answer:
The earliest users of the Oregon Trail were trappers, traders, and explorers rather than members of the Lewis and Clark expedition. Over 400,000 settlers used the trail to migrate west during the peak period of 1845 to 1870, influenced by the American desire to expand into new territories.
Step-by-step explanation:
The earliest users of the Oregon Trail were not members of the Lewis and Clark expedition. Instead, the Oregon Trail was carved out by trappers, traders, and explorers and was later used by a large wave of settlers and immigrants. This trail spanned about 2,000 miles from Independence, Missouri, to Oregon's Willamette Valley. During the peak migration period of 1845 to 1870, over 400,000 settlers followed this path westward, motivated by factors such as the American desire to expand and the quest for new opportunities.
The Lewis and Clark expedition, on the other hand, was a separate earlier exploration led by Meriwether Lewis and William Clark between 1804 and 1806. While their journey did open up the West for future explorers and settlers, it was not a part of the Oregon Trail migration that occurred later. The expedition sought to discover commercial possibilities and potential trade routes through the newly acquired western lands of the United States, mapping the territory and establishing relationships with Native American tribes.