What concepts were applied during the Lewis and Clark expedition?

One of Thomas Jefferson's goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He also placed special importance on declaring US sovereignty over the land occupied by the many different Indian tribes along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission.