In order to receive the benefits of railroads, they must cover one province in the state in which the factory is situated. Otherwise, they will not be effective. The average railroad efficiency of the state is calculated and used for factory purposes; the more railroads you have in the state, the higher the efficiency. Never forget the importance of railroads in improving factory efficiency; it can make all the difference in the world in the later game. Besides, railroads are always a good investment because they also allow your troops to move across your territory much more quickly than they otherwise could.