Rails-Across-America

Another popular railroad board game available playing online. Your attempt to railroad the United States into falling under your monopolistic thumb, you'll need to build tracks connecting to the many cities present on the map of the US and some in Canada and Mexico. But the goal here isn't really the money you make, but the prestige you gain from building the most and longest lines.



Unfortunatelly I haven't found free version but you could buy it here.
Some cheat codes here.

Ticket to Ride

Easy to play railway building games but with lots of strategies. Connect cities across the USA for high scoring routes. Colorful board and great little trains.

Read more about the game at wikipedia.

And of course play it online.



Source of picture: http://en.wikipedia.org/wiki/Ticket_to_Ride_(board_game)