The Third and Townsend Depot was the main train station in the city of San Francisco for much of the first three quarters of the 20th century. The station at Third Street and Townsend Street served as the northern terminus for Southern Pacific's Peninsula Commute line between San Francisco and San Jose and long-distance trains between San Francisco and Los Angeles via the Southern Pacific's Coast Line. For service for destinations to the north, such as Seattle, and destinations to the east, such as Chicago, passengers generally needed to travel to Oakland, initially on ferries to Oakland Long Wharf, and later on buses to 16th Street Station. It was demolished in the 1970s and replaced by the Caltrain commuter station a block away at Fourth and King Streets.

San Francisco 4th and King Street station, also known as the Caltrain Depot, is a train station in the SoMa district of San Francisco, California. It is presently the northern terminus of the Caltrain commuter rail line serving the San Francisco Peninsula and Santa Clara Valley. It is also the eastern terminus of the N Judah and E Embarcadero, as well as a stop along the T Third Street of the Muni network. The station is additionally the projected terminus for the first phase of the California High-Speed Rail project and a station once Phase 2 is completed.