A union station (also union terminal or joint station) is the term used for a train station where tracks and facilities are shared by two or more railway companies, allowing passengers to connect conveniently between them. The term 'union station' is used in North America and 'joint station' in Europe.

Historically, a union station was used by all passenger trains serving the city. Today, this is not necessarily true. In Chicago, Illinois, for example, commuter trains use four different terminals, while the city's Union Station handles all intercity traffic.

In North America, a union station is usually owned by a separate corporation whose shares are owned by the different railways which use it, so that the costs and benefits of its operations are shared proportionately among them. This contrasts with the system of trackage rights or running rights, where one railway company owns a line or facility, but allows another company to share it under a contractual agreement. However, the company that owns the union station and associated trackage does assign trackage rights to the railroads that use it. Many of the jointly-owned stations were built by terminal railroads. Examples include the Ogden Union Railway & Depot Company, jointly owned by Southern Pacific and Union Pacific to manage the Ogden Union Station in Ogden, Utah, and the Denver Terminal Railway Company, representing the Denver & Rio Grande Western, Chicago Burlington & Quincy, Union Pacific, Atchison Topeka & Santa Fe, Colorado & Southern and Chicago Rock Island & Pacific railways, which managed the station in Denver, Colorado.