Thanks to Scott for his comments regarding Sam's railroad trip back to
Saint Louis from New York in 1854. Yes, Sam almost certainly would have
taken the Pennsylvania Railroad to Pittsburgh, however after a bit of
follow-up research, I don't believe that he took the Ohio and Mississippi
Railroad from Cincinnati on the last leg of the trip. instead, I believe
that he took the
*Pittsburgh, Cincinnati, Chicago and St. Louis Railroad*, commonly called
the *Pan Handle Route:*

https://en.wikipedia.org/wiki/Pittsburgh,_Cincinnati,_Chicago_and_St._Louis_Railroad
)
https://www.hookedtobooks.com/funny-mark-twain-quotes/
The information in the Wikipedia article appears to be somewhat
contradictory.  However, it appears clear that Sam's path from Pittsburg
went through Columbus. From there, we can't really be sure based on the
information it supplies whether he went to Cincinnatti at all on that trip.
The map in the Wikipedia article indicates that the more direct route to
Indianapolis had been completed. However, the article equivocates about
when it was completed. From the standpoint of my story, it doesn't really
matter either way, as Sam continued through without stopping... however it
would be nice to know!
    I came across a reference previously that Sam paid $23.50 for the trip.
    Regarding the relative price between coach and sleeper cars, this is
what Wild West Magazine says:
    Passenger train travel during the 1880s generally cost *two or three
cents per mile*. Transcontinental (New York to San Francisco) ticket rates
as of June 1870 were $136 for first class in a Pullman sleeping car, $110
for second class and $65 for third, or “emigrant,” class seats on a bench.Jun
25, 2018

    Thanks again for your help!
Peter