Pickering with limited rush hour train service to Hamilton. This line, now divided as the Lakeshore East and Lakeshore West lines is the keystone corridor of GO Transit, and continued to be its only rail line for its first seven years of operation. GO's other five lines were opened between 1974 and 1982, significantly expanding the rail network from 86 to 332 kilometres long, and from 16 to 43 stations.

To that point, all of GO's rail services ran