The Metro Boston and the Massachusetts Bay Transportation Authority (MBTA), is "a body politic and corporate and political subdivision" of the Commonwealth of Massachusetts formed in 1964 to finance and operate most of the buses, metro systems, and ferry in the Greater Boston (Massachusetts). Formerly called the Metropolitan Transit Authority (MTA), but was replaced by the MBTA and immortalized by the Kingston Trio in popular protest lament "MTA." Bostonians call it simply as "T" for its logo, which is the letter T inside a circle, adopted at the 60. In 2006, the average runs of the system was 1.1 million a day, 2 being the average of 598,200 passengers for making Boston7 meter more concurrent fourth system in the United States. The Green Line and Line Ashmont Mattapan High Speed T is the light rail lines busiest in the United States, with an average of 255,100 passengers per day. The MBTA also operates its own police agency, the Transportation Authority Police Massachusetts Bay. In 2006, 31.60% of workers within the city limits of transport used public.