Why do the NO HUNTING signs in my area always say POSTED, too?

All of the No Hunting signs I’ve ever seen in my area (Maryland and West Virginia) look like this, as opposed to the No Trespassing or No Soliciting signs, which simply state their message. It just seems kind of redundant. I mean, I can see that the sign is posted, can’t I? Why do they feel the need to tell me, too? Is there a legal reason that Posted has to precede No Hunting?

While searching for images to use in this question, I noticed that you can buy signs that don’t say “posted”, but I’ve never seen one here. Could this be a regional thing?