Source: International Union of Railways.
The quantity of freight carried by rail is related to country size and the composition of the economy. Large countries imply longer national distances over which rail freight is carried, which results in more ton-km for an equivalent quantity of freight. Countries endowed in natural resources usually involve more rail tonnage. The United States, the Russian Federation, China, Canada, Australia, and South Africa are all large countries where a substantial amount of natural resources are being carried by their rail system.