A transcontinental railroad or transcontinental railway is contiguous railroad trackage, that crosses a continental land mass and has terminals at different oceans or continental borders. Such networks can be via the tracks of either a single railroad or over those owned or controlled by multiple railway companies along a continuous route. Although Europe is crisscrossed by railways, the railroads within Europe are usually not considered transcontinental, with the possible exception of the historic Orient Express. Transcontinental railroads helped open up unpopulated interior regions of continents to exploration and settlement that would not otherwise have been feasible. In many cases they also formed the backbones of cross-country passenger and freight transportation networks. Many of them continue to have an important role in freight transportation and some like the Trans-Siberian Railway even have passenger trains going from one end to the other.