Found this today in an antique shop.  It’s a pinback. The diameter is 1.5″ or 3.8cm.  I see several of these around on the internet, all noted as being “vintage”.  Southern went under the control of Norfolk-Western in 1982 and then was merged officially into the Norfolk Southern Railroad in 1990.
I could go out on a limb and say that this may date to before the railroads gave the old heave-ho to passenger service in this area, but I won’t.  That’s definitely a diesel engine on the left, though.  The caboose on the right fits the streamlined period, but that may just be to fit the design on this pin.

Basically, I just don’t know when these were handed out.

This one is in fair shape.  Water damage, apparently, around the rim.