"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 (Coast to Coast) and 18OE being the others). There are 30 railroads, hundreds of freight and passenger stations and 9 different sizes of trains.
26 copies of this game exist individually lettered A, B, C, ......Z.