Canal Street opened as the line was extended south to South Ferry from 34th Street–Penn Station on July 1, 1918, and was served by a shuttle. The new "H" system was implemented on August 1, 1918, joining the two halves of the Broadway–Seventh Avenue Line and sending all West Side trains south from Times Square. An immediate result of the switch was the need to transfer using the 42nd Street Shuttle in order to retrace the original layout. The completion of the "H" system doubled the capacity of the IRT system.