One of the latest postings on their site is of mile markers along the old National Road in Maryland.
Mountainjunkie posted a photograph of the MM 79 stone, which means 79 miles to Baltimore was shown and a short history of the road given. The National Road has now been replaced by US-40.
Quite a few of these markers still are around, but some are illegible. Some have been destroyed in vehicle accidents.
You can also see pictures of MM 82 to B, MM76 to B, and MM 75 to B under the US Historic Survey Stones and Monuments.
Sure Glad We Got the New SDignage in the 1920s. --RoadDog