The Tuscarora Trail (including the Big Blue section) was built as a speculative alternative route for the Appalachian Trail. It was built further west, in a more wild corridor, because it was feared that development would force closure of the AT, before the Federal effort to conserve that trail.
Much of the trail in Pennsylvania was closed in the 1980s because a gypsy moth onslaught had killed much of the surrounding oak forest. The trail became overgrown with brambles, briars and other vegetation to become impassable. The trail has since been re-opened and is now maintained by the Potomac Appalachian Trail Club.
The Tuscarora Trail is today an official side-trail of the Appalachian Trail and is blazed in blue.