Lakeshore West is one of the seven train lines of the GO Transit system in the Greater Toronto Area, Ontario, Canada.

[4] The first train, numbered 946 left at 5:50 am from Oakville bound for Toronto, ten minutes before service began out of Pickering.

The experiment proved to be extremely popular; GO Transit carried its first million riders during its first four months, and averaged 15,000 per day soon after.

[6][7] Service began running west from Union, stopping at Mimico, Long Branch, Port Credit, Lorne Park, Clarkson, and Oakville.

Rush-hour trains ran to Bronte, Burlington and Hamilton, at the former CN railway station at James Street.

The opening of Aldershot coincided with the extension of all day and weekend service from Oakville to Burlington, however, this was reversed due to budget cuts on July 3, 1993.

Combined with additional work undertaken since the early 1990s, this gives the Lakeshore West line at least three tracks from Union Station through to Bayview Junction.

[23] Originally planned for completion in 2023, Metrolinx halted the delivery process for the stations in the Niagara extension in November 2018 when the newly-elected 42nd Parliament of Ontario rescinded its funding for their construction.

[32] On March 31, 2010, GO acquired its first segment of the Oakville subdivision, between Union Station and 30th Street in Etobicoke (just west of GO's Willowbrook Rail Maintenance Facility).

[34] On March 22, 2013, Metrolinx purchased a third segment extending its ownership westward to a point just west of Burlington station, where the CN Halton Subdivision joins the line.

[35] In addition to the Union Station Rail Corridor, these three segments represent Metrolinx's current ownership of the line.

CN continues to own the tracks between Burlington and the Desjardins Canal, as well as the Grimsby subdivision that carries trains into Niagara Region.