The State Belt Railroad begain in 1889 for the sole purpose of handling freight traffic along San Francisco's waterfront. Its name is derived from the fact that waterfront property at the time was owned by the State of California, and not the City of San Francisco. (When California was originally surveryed, the land along the waterfront was underwater, and thus was not included in San Francisco city limits.)
The State Belt Railroad saw traffic from both the North Pacific Coast Railroad and the South Pacific Coast Railroad; as both railroads had different gauges, a majority of the State Belt Railroad's tracks were dual-gauged to accommodate. In addition, interchange with both railroads was done by ferry as the State Belt Railroad had no physical connection with the nation's rail network; this changed in 1913, when SBRR's tracks finally joined with Southern Pacific trackage at a small interchange yard. At the height of the State Belt Railroad, 67 miles of track were in its service.
Freight service began to dwindle as shipping routes started terminating in Oakland, across the San Francisco Bay. In 1969, the State sold the water front property to San Francisco, and the State Belt Railroad was promptly renamed the San Francisco Belt Railroad. 1993 saw the railroad company come to an end, with a majority of tracks already abandoned by this time.
Parts of the former main belt line have been rebuilt as the Muni (light rail) Embarcadero line. Some of the freight piers have been refurbished as restaurants; some others are used as parking/storage facilities.