I have attempted to identify Mark Twain's travel routes and railroads 
for his "Three Speeches Tour", October 1871 to January 1872.  
Identifying railroads can be quite tricky as one is never sure what a 
particular railroad's name is at any particular time: who owns, it, who 
is leasing it, who is controlling it. I have already identified some 160 
railroads associated with Twain at one time or another.  Many are 
actually the same line with a different name.

The maps are displayed using the Google engine and can be made full 
screen and enlarged.

http://twainsgeography.com/content/three-speeches-tour-1871-72