Then one day it occurred to me that my old friend Becky Royalty lived only a few hundred feet away from the place all through her childhood. Alas, she too had forgotten -- but her brother Troy hadn't. At last I had the answer. It was Mister S, he said. I thought when I heard the name I would slap my knee and say, "Yes, of course! Now I recall!" But that's not what happened. "Mister S? Is he sure?" I asked. Then Dave Conover saw my post on Facebook and found this clipping of a Mister S from a Lorain, Ohio newspaper. It was only when I saw the S at the top of the sign did a rather bent old penny drop. The caption states Lorain's own Mister S was apparently quite special -- it was the pilot plant of a brand new chain. Logic suggests that Mister S may have been based in Ohio.
Here's an ad printed in the classifieds of The Courier-Journal (Louisville, KY) from March 9, 1965. I found similar ads in newspapers in Ohio and Michigan.
Note the interesting perspective.
I also found this drive-in restaurant forum from over a decade ago and this post from a blog about Lorain County.
Here's an article from The Times-Recorder (Zanesville, Ohio) from February 11, 1968 about the local Mister S opening up on 1115 Newark Road (the article has the address wrong).
It's very possible the Dixie Highway location was only the one in Louisville -- and possibly in all of Kentucky if the chain sputtered out as quickly as I suspect it did. Sometime around 1970 it became a locally owned restaurant called Poynter's Pups, but that didn't last long either. Much to my surprise, and though extensively modified, the building itself exists today. But if you look closely, you can still see portions of its mid-century modern steel frame. The massive signage structure, however, has disappeared.
Another conversion in Farmington Hills, Michigan. In this case, the top of the sign was also cut back, but the original shape of the Mister S lower signage remains intact.