Hidden signs of Greenwood

Along Old Excelsior Road in Greenwood,(population 688) set back about 20 ft from the road there are two billboards. When the leaves have fallen from the sumac the two signs are visible. They are numbered for licensing purposes, I am sure. The signs are set in a ravine, and I assume it has been a long time since they served any advertising purposes. Just a curiosity to me, I stopped and took a photo.