The San Francisco Municipal Railway (SF Muni or Muni) is the public transit system for the city and county of San Francisco, California. In 2006, it served 46.7 square miles (121 km2) with an operating budget of about $700 million. In ridership 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 Metro in Los Angeles. 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.