The first municipally owned streetcars take to the streets in San Francisco.

The San Francisco Municipal Railway (SF Muni or Muni) is the public transit system for the City and County of San Francisco. Despite the name, the network has 54 bus lines and 17 trolleybus lines, in addition to seven light rail lines (called Muni Metro) that operate above ground and in the city's lone subway tube, three historic cable car lines, and two historic streetcar lines.

Muni is an integral part of transportation in the San Francisco Bay Area, operating 365 days a year and connecting with other regional transportation services, such as Bay Area Rapid Transit (BART) and Caltrain commuter trains, along with AC Transit, Golden Gate Transit and SamTrans buses, and ferries from Golden Gate Ferries and San Francisco Bay Ferry.

In 2018, Muni served 46.7 square miles (121 km2) with an operating budget of about $1.2 billion. In ridership terms, Muni is the seventh-largest transit system in the United States, with 210,848,310 rides in 2006 and the second largest in California behind the Los Angeles County Metropolitan Transportation Authority. With a fleet average speed of 8.1 mph (13.0 km/h), it is the slowest major urban transit system in America and one of the most expensive to operate, costing $19.21 per mile per bus and $24.37 per mile per train. However, it has more boardings per mile and more vehicles in operation than similar transit agencies.