(covers information from several alternate timelines)
A cable car was a type of tram that operated on a cable railway. These cars were used for transporting passengers and for advertising products. Signal lights governed the movement of the cars. In San Francisco, the cable car system was operated by the San Francisco Municipal Railway and, later, Trans Francisco. One of the lines on this system was Powell & Mason.
In 1986, as Pavel Chekov and Nyota Uhura were attempting to get directions to the nuclear vessels docked at Alameda from passersby, a Powell & Mason cable car filled with passengers was seen making a left turn. They spoke to an SFPD officer who stood near traffic light posted with a sign that read "cable car signal only". (Star Trek IV: The Voyage Home)
By the mid-23rd century, in the alternate reality, the cable cars had been equipped with anti-grav devices. In the aftermath of the USS Vengeance crashing into the city, one of these cars could be seen traveling down a road. (Star Trek Into Darkness)