"1831 is a railroading game like no other. It combines the real spirit of the original Robber Barons with both common and preferred stock, hostile takeovers, passenger and cargo routes, and a game map that accurately reflects real terrain." (quote from the rules overview)
This is one of the three largest 18xx games (18C2C: Manifest Destiny and 18OE: On the Rails of the Orient Express being the others). There are 30 railroads, hundreds of freight and passenger stations and 9 different sizes of trains.
26 copies of the original edition of this game exist individually lettered A, B, C, ......Z.
The game was republished in 2014 by All-Aboard Games.