Quoting the site:
For each day of the Lewis and Clark expedition two hundred years ago I post, on the corresponding day in the present, a little summary of what the expedition did on that day and also a little summary of something else that happened in American history on that day.
I always like sites like this that tell us about the stories we missed because of other events. I can only imagine what we would’ve heard about had we not gone to war, for example.