When people attempt to retrace the Expedition’s complete, exact route, they usually give up in many places because “civilization” has overrun the trail—homes, industry, dams, etc. They will try to get as close as possible then bypass the civilized area. The other big obstacle is the difficulty for many people to read Clark's survey notes.
But there are other places where “boots on the ground” prove that what might have been surveyed, was actually modified when the Expedition used it, because of the topography. Surveys go in a series of straight lines and can plot a course through a steep canyon or other obstacle the users must reroute around.
Nothing gives a better understanding of the details of history than an accurate re-creation of it.