This is one of the routes on the Underground Railroad.
The Underground Railroad was an informal system that helped slaves escape to the northern states and Canada. It is not underground nor is it a railroad. It got its name from a slave owner whose slave had ran away, and since he couldn't find him, he assumed he had used an underground railway.
    The slaves followed the North Star and the moss. Moss only grows on the north side of trees. Free African Americans and Quakers(Caucasian abolitionists) provided food, clothing, directions, and hiding spots for the slaves.