"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 two largest 18xx games (18C2C being the other). There are 30 railroads, hundreds of freight and passenger stations and 9 different sizes of trains.
Only about 50 copies of this game exist.
