Say what you will about Arkansas highways and AHTD's signing practices, they always seem to do amusing/odd things. One of my favorites is posting the wrong route shield.
Now, I can sort of see how someone might become confused: this road was US 59 back in the mid 1930's. Well, it was actually TEMP US 59. Oklahoma was upgrading old OK 17 to be part of US 59 so it was temporarily detoured through western Arkansas...but that was 70 years ago! This has been State Route 59 since at least 1940.