The first subway in Canada (opened in 1954), the Toronto Subway is one of the most heavily used on the North American continent. Operated by the Toronto Transit Commission (who also operates Toronto's streetcar and bus systems), the system covers 69 stations with about 68 kilometers of track.

The lines of the system are as follows:

* Yonge-University-Spadina Line: Shaped like a U and colored yellow on the system map, this line is the oldest in the system (wtih the Eglington-Union stretch opening in 1954) as well as the most heavily used. Currently, an extension into the suburb of Vaughn is to be opened in 2016.

* Bloor-Danforth Line: Covering an east-west axis about 2 to 3 kilometers inland from Lake Ontario, this line is the second oldest, second buisiest and second longest in the system. The first portions of it opened in 1966 after being in the planning stages for several years. Currently, the line has no extensions planned.

* Scarborough RT: A bit off an odd subway line, the Scarborough RT was opened in 1986 and runs through the district of (you guessed it) Scarborough. The line, unlike the rest of the system, uses different rolling stock, different track gague and different means of propolusion. It was originally going to be a streetcar line, but politics turned it into what it is today. However, the line is to be demolished and replaced with streetcars after the Pan American Games in 2015.
** As of September 2013, it's going to be a subway. That's likely not going to be the last of it.

* Sheppard Line: The newest line in the system (opened in 2003) as well as the shortest and least used, the Sheppard Line services the growing Sheppard Avenue corridor in North York. There aren't many interesting things to say about this line, though, besides the fact that it is close to fully underground.

Intersting facts about the subway include:

* All lines (except for the aforementioned Scarborough RT) are not standard gauge (4 foot 8 1/2 inches) -- rather, they are slightly wider (4 foot 10 7/8 inches). This is because the subway tracks were designed to match the gauge of Toronto's streetcar system (and part of Toronto's subway system was originally planned to be serviced by existing streetcars). The reason for the non-standard gauge for Toronto's streetcars appears to be that the city wanted to make it impossible for the streetcar tracks to be used for freight cars, and excluded them through the use of a wider gauge. Historic Toronto transit equipment must be re-gauged if it is to operate elsewhere.
* The system only has one abandoned station, which is actually just part of a station. The abandoned station is the lower level of Bay on the Bloor-Danforth Line, which was only in service for a few months as part of a unique (but ineffecient) service plan to have all stops served by at least two lines. The station does often appear in film, though, as it commonly doubles for a New York subway station.
** There is another Toronto subway station with an extra level that was never used. When the Queen Street subway station was built, it was originally planned to interchange with an underground streetcar line that would be built along Queen Street downtown, and the station for this line was “roughed in” below the existing Queen Street station on the Yonge line. The subterranean streetcar line was never built, and thus the lower level has never been occupied.

* The system has it's own font, which is called... wait for it.... Toronto Subway Font. It is used in most, if not all, stations.