The Massachusetts Bay Transportation Authority (MBTA) is "a body politic and corporate, and a political subdivision" of the Commonwealth of Massachusetts [1] formed in 1964 to finance and operate most bus, subway, commuter rail and ferry systems in the greater Boston, Massachusetts, USA area. It replaced an earlier agency called the Metropolitan Transit Authority, or the MTA, as immortalized in the popular Kingston Trio folk-protest lament "The MTA Song". It is known by the locals as simply The T because of the logo it adopted in the 1960s, that of the letter "T" in a circle. In 2004, the entire system averaged 792,600 one-way passenger trips each weekday. The subway averaged 598,200. The Green Line of the T is the busiest light rail system in the country.