The marker is a concrete wall that says "Lincoln Highway" on the one side and "County Road" on the other. Unless you are familiar with Boone, this marker is often overlooked.
To locate the cache, go behind the marker, and check the bush to your left.
When hiding this, I noticed a container in the right bush. Upon further investigation, I found it to be a letterbox associated with AtlasQuest. Please do not use that container to claim a find, and unless you participate in Atlas Quest, please leave that container alone.