No maker of stream markers has ever been determined
Originally known only from photo in book "Brandywine - A Pictorial History" by William Baldwin (located by JGl). Marker is believed long gone and only the post remains. As of December 2020, signless post is laying behind guide rail. KMT has requested PennDot to remove it for safe keeping and reuse.
From book by Wm. Baldwin
May 2013 photo by JGL
Dec. 2020 photo by JGL
U.S. Route 322 South of Downingtown
Now a signless post only