Toronto–York Spadina subway extension

The Toronto–York Spadina subway extension (TYSSE) is an extension of the Toronto subway's Line 1 Yonge–University which opened on December 17, 2017. It runs 8.6 kilometres (5.3 mi) northwest from the line's previous terminus at Sheppard West station serving six new stations and terminating at Vaughan Metropolitan Centre station near Jane Street and Highway 7 in Vaughan. The TYSSE was the first new section of a Toronto subway line to be opened since the opening of Line 4 Sheppard in 2002.

The extension was first envisioned in the 1980s, though the route of an extension to York University was not finalized until 2005. Despite the lack of development there at the time, an extension to Vaughan was added and construction began in 2008. Initially expected to open in time for the 2015 Pan American Games, the extension went overbudget and opened two years after originally planned. The new stations were among the first to eliminate collector booths and Toronto Transit Commission (TTC) fares are charged at the Vaughan stations. Upon opening, most stations on the extension saw below average ridership compared to the rest of the subway system.