Sherry Smith-Stanford

Just found this forum, an thought I might ask a question. I know what the markers for the PPOO looked like, red and white band with PPOO, but were they also marked with an "R" or "L" where one was to make a right or left turn? I thought I read that somewhere, but now can not find my reference. I may be buying an old gas station in Newman, IL that was on the route, and was called the "Ocean To Ocean" Filling Station. Thanks so much for any help. sherry