The railroads play a large part in my Twain's Geography project and 
lately I've been reading about the labor strikes, the most significant, 
it seems, was the Pullman Strike and its expansion out to a near general 
strike of all industries.  I've been searching for any comments Twain 
might have made about this, to no avail.  He had personal ties with 
railroad industrialists, including H. H. Rogers, so he must have been 
aware.  So far the only results of searching point to comments on the 
Pullman cars and the people that used them, not on the socioeconomic 
ramifications of these events.

Twain was very much concerned with those sitting in darkness in other 
countries but not so much with those in this country.  I don't have 
access to letters not already publish on the Mark Twain Project's site 
and the events in question occurred in this later period.