The Natchez Trace runs, as the post title says, from Natchez, Mississippi, on the Mississippi River itself, to just south of Nashville, Tennessee. It's 444 miles long and is, itself, a national park, administed by the National Park Service. It is a limited access highway with a maximum speed of 50 miles per hour. Since no commercial traffic is permitted and there are few gas stations (I actually know of only one which closed down a few years - I'm not sure if there are any further north), the big RVs seldom travel it. In fact, except for certain stretches few vehicles travel it at all because it's only two lanes, the speed limit is strictly enforced, it is poorly or not at all lit, and the woods are full of deer and other animals.
I love it.
Because of the danger of hitting a deer at night, I travel it very slowly and stop often just to be in the middle of the Mississippi wilderness.
I looked at one video which was a time lapse of the entire trace and, as time lapses do, the entire distance was covered in a matter of minutes, giving you the impression you were traveling at 100 mph. Nothing could be further from the actual experience. The trace is for taking your time and savoring.
Oh, here is the Wikipedia entry about the historical trace.
Note: this beautiful road / national park would not have been built without the backing of Franklin Delano Roosevelt - FDR: Another wiki..