List of tram systems by gauge and electrification
The following is a list of tram/streetcar (including heritage trams/heritage streetcars), or light rail systems with their track length, track gauge, electrification system. The vast majority of tram systems use . Generally, standard gauge is the standard for every brand new system (except for the former Soviet Union), even in places where there is another gauge for the heavy rail. Metre gauge is mainly present in some old, continuously operating systems in Central Europe. Russian gauge is used only in the former Soviet Union. While in Central Europe the standard gauge  and metre gauge coexist, in the former Soviet Union only the Russian gauge is used. The electrification system for the old systems is generally 600 V DC while the more recent systems use 750 V DC. Some old systems upgraded to 750 V in recent year (mostly in Germany) while some system (in Romania) downgraded the voltage to 600 V to use the second hand vehicles coming from the upgraded German networks. Few systems are partially or wholly catenary-free, with APS and ACR systems or using a pure internal power source as battery or ultracapacitors. Very few vintage systems  are horse-drawn tram or cable car. For references for the figures, see each system's page. Systems in operation. Note: Overhead line electrification unless specified differently