The San Francisco trolleybus system forms part of the public transportation network serving San Francisco, in the state of California, United States. Opened on October 6, 1935, it presently comprises 15 lines, and is operated by the San Francisco Municipal Railway, commonly known as Muni (or the Muni), with around 300 trolleybuses. In San Francisco, these vehicles are also known as "trolley coaches", a term that was the most common name for trolleybuses in the United States in the middle decades of the 20th century.