|a public vehicle running regularly along certain streets, usually on rails, as a trolley car or trolley bus.
A streetcar is one of the oldest forms of mass rail transit. In the early 19th century streetcars were pulled by horses and by the end of the 19th century electricity had taken over as the power that ran the cars.
Streetcars (or trams) are a heavier use replacement for busses along a corridor that supports higher density. Since streetcars operate in mixed traffic along with other automobiles (the same as busses) it is subject to much of the same traffic congestion that automobiles are but areas close to a streetcar line typically exhibit a much higher density than those that aren't. Because of this propulsion of density surrounding a streetcar line, the additional taxes brought on by the higher density helps to justify the costs associated with such a mass transit option.