- Main article: Railroad (Imp1)
Construct a section of railroad by having an engineer in one of the tiles you wish to join and clicking on the target tile.
If you have the technology required to build into the target terrain and the terrain the engineer is on, you should see an icon of railroad track above the target tile before clicking. Swamps, hills, and mountains are not available at the start of a standard game. Swamps become available soonest, in about 1821 with the purchase of the Iron Railroad Bridge technology.
The subsidiary value of your transport system, in addition to its regular job of carrying items to your capital, is the rapid movement of Army units to non-adjacent provinces (even overseas). An attempt to move them will show a black railroad engine icon. However, the caoacity for that is based on your number of freight cars, not on your length of railroad.
In Imperialism 2 you must wait for the research of Early Steam Engine before you can build railroads. Even then, they can't immediately go everywhere. But wherever they go, they increase your resource haul per tile from 2 to 4.