Here is an example of the Mason-Dixon stone at mile marker 50. It’s called a Crown stone and only exists every 5 miles. This is the Maryland side. The rest have M’s & P’s on the stones. As I understand it, this is a replacement stone, but it shows what they look like in very good condition. We found Mile 55 and it was in a cage. I guess it tried to escape.
This stone is in great shape. You can see the circle carved around the letter 240+ years ago. The green marker is a US Coast & Geodetic known place on earth.