Photo courtesy of David Backlin (taken August 2005)
Signs such as this white-on-black left-turn advisory sign were once extremely common in Missouri. I remember many of these being installed on Business Loop 70 in Columbia around 1966 and 1967. All of those signs are gone now, but David Backlin found that this one in Poplar Bluff was still around in 2005. The button reflectors on the sign were still present, but David says that they are "barely noticeable".