A union station (also known as a union terminal and, in Europe, a joint station) is a railway station at which the tracks and facilities are shared by two or more separate railway companies, allowing passengers to connect conveniently between them. The term ‘union station’ is used in North America and ‘joint station’ is used in Europe.
In the U.S., union stations are typically used by all the passenger trains serving a city, although exceptions exist. For example, in Chicago, the Illinois Central and Chicago & North Western depots coexisted with Union Station, and although most Metra commuter trains (and all Amtrak services) continue to use Union Station today, some lines depart from other terminals, such as Millennium Station.
The busiest station to be named “Union Station” is Toronto Union Station, which serves over 72 million passengers annually.