The Old Trace; a remnant of one incarnation of the Natchez Trace, a wagon trail that ran from Natchez, MS to Nashville, TN created on orders from President Jefferson in the early 19th century; it was probably originally a game trail by which bison and other large animals reached the salt licks around Nashville.
Later in the just previous century it was smoothed, bridged and paved and ultimately turned into our longest and thinnest national park: 440 miles long by about the same number of yards wide.
The opening of the Midwest after the Revolutionary War was challenged by difficulties of transporting farm products back over the Appalachians to population centers.
The easiest way to ship produce was by flatboat down the Ohio and Mississippi Rivers to the port of Natchez for transshipment through the Spanish Port of New Orleans by ocean.
Flatboats float downstream very well. Their abilities in the other direction were such that they were sold for lumber at the port and the captain and crew had to get home on their own. The shortest way home was through the woods to the headwaters of the Cumberland River at Nashville.
It was a long, typically wet and always dangerous slog. And remember if you're going north on the Trace, you are presumably carrying the proceeds of your venture down the river.