All railroads begin on the eastern edge of the map. Since cities on the opposite edge take more time and effort to reach, city values increase as you move west. One person starts the game with a wooden train marker, indicating that she will play first. In each round, players may expand any of the five railroads by laying an appropriately colored track segment. Finally, players replenish their hands and the train passes to the next player.
Players start the game with a hand of cards corresponding to cities on the map.
Each player lays one card face up at the start of each turn. At the end of the game, players earn points according to the number of different railroads which service the cities for which they've played cards. Thus, by playing a city card a player effectively warns his opponents that he'll be trying to steer railroads into that city. As a result, it is often better tactically to hold onto a city card until after some railroads are already connected to that city so other players won't be able to spoil your plans. Of course, it isn't always possible to wait that long.