Marion to Tazwell - The Back of the Dragon, a 29 mile long section of VA 16 runs north / south between the towns of Marion and Tazwell, Virginia. Climbing up and down the mountain ridges along the way it holds both sweeping curves in the valleys and tight and twisty sections carving through the rocky cuts in the high parts. There is little along the way, a few homes and farms. Most of it is wooded passing through Hungry Mother State Park at the south end. It is a useful road, one of the nicest ways to traverse this area, easy to work into your travel plans. Over the years it has been popularized and marketed as a motorcycle destination ride. The hub of this motorcycle related activity is at the north end in Tazwell where the Back of the Dragon Visitor Center opened a new facility in 2020. Several good rides connect to it and there is some great riding in the surrounding area.
I was chatting with PlushParu(https://miles-by-motorcycle.com/157623) this evening about gravel roads in Pennsylvania. Most states offer up datasets of their unpaved roads. After some googling around I did find a dataset covering gravel roads in Pennsylvania: Pennsylvania Spatial Data Access | Data Summary(https://miles-by-motorcycle.com/136/links/163338/pennsylvania-spatial-data-access---data-summary) It dates back to 2012. They do not offer their data in GPX format but they do support the ESRI Shape File format which is included in the zip download. ESRI Shape files can be converted to GPX using GPSBabel. It's pretty large at 63MB so too big for the prototype mapping tools I have here on the site. But it should load (albeit slowly) once I get the new editor fielded Any Day Now(tm), which I've been saying for something like I year.