 Ninth Street opened on June 22, 1915, as part of an extension of the subway to Coney Island station, which included the Fourth Avenue Line north of 59th Street as well as the entire Sea Beach Line.The station's opening was marked with a competition between two trains heading from Chambers Street station in Manhattan to the Coney Island station, one heading via the West End Line and the other via the Sea Beach Line; the latter got to Coney Island first.On June 27, 1922, the New York State Transit Commission directed its engineers to prepare plans to lengthen the platforms at 23 stations on the lines of the Brooklyn–Manhattan Transit Corporation (BMT), the successor to the BRT, to accommodate eight-car trains.