This stone is at Mile 100 of the Line...right in somebody's front yard (would that be cool, or what!?).
[image credit Gary]
I have previously posted about The Line here and here. Per the Maryland Historical Society,
The Mason and Dixon Line (or Mason-Dixon Line) runs for 233 miles along parallel 39°43 in the eastern United States, marking the boundary between Maryland and Pennsylvania. The line was surveyed by English astronomers Charles Mason and Jeremiah Dixon in 1763-1768 to settle property disputes between the Penns and the Calverts, proprietors of Pennsylvania and Maryland, respectively.
This is a great site for on-the-ground stone location information. I've found it very useful and specific.
The link to Ultrarunning is that I LOVE to combine training runs with history. Having a destination to run to or past, packing a camera, is so exciting, espeically if there is an element of searching or discovery involved. Plus the notion that you are checking something out that never even appears on the radar screens of most "normal" people.
I can't count the times when I've been having a discussion about, say, geography, with somebody, and when I mention the Appalachian Trail, or the Skyline Drive, or the Mason-Dixon Line, all I get are blank stares. It's kinda sad, actually.