Cortlandt 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. The station was built at the intersection of Cortlandt and Greenwich Streets, in a part of Lower Manhattan nicknamed "Radio Row" because of the many electronics dealers on the street. It had a standard two side platform layout with two tracks. There were mosaic decorations by Squire J. Vickers or Herbert Dole depicting ships along each platform's wall. Red i-beam columns ran along the entire length of both platforms at regular intervals with every other column having the standard black station name plate in white lettering; the name plates alternated between "Cortlandt Street" and "World Trade Center".