The float above has Miss Mercer County on it. Zooming in on the dates showed 1803-1953, the dates of Ohio's Sesquicentennial.
I was curious about the movies playing in the theater they were passing. Young Bess is about the life of Elizabeth I before she became queen and starred Jean Simmons, Stewart Granger, and Deborah Kerr. In The Atomic City, an atomic scientist's son is kidnapped by enemy agents. It starred Gene Barry, Lydia Clark, and Michael Moore.
Update from an email I received: There is a cemetery next to the quarry (Swamp College) and this could be the carriage used at the cemetery with Karch’s name on it for advertising the quarry.
The Chamber of Commerce float wraps it up with "Come Back to Celina" on the back!