Hi,
The PRR route through Marion was originally part of the Grand Narrow Gauge Trunk - Toledo, Cincinnati & St. Louis. This line was to have been a big 36" gauge trunk line extending from Ohio to Texas. It failed for many reasons. The book
American Narrow Gauge Railroads by George W Hilton covers this line very well.
When the TC&StL failed, the line was divide up and the PRR got the The section at Marion. It was sort of the way the Chicago Rock Island & Pacific was cut up in the c1980 bankruptcy.
Doug vV