[5][7] STE also took over the Compañía de Ferrocarriles del Distrito Federal (Mexico City Railways Company) at that time.

These have all since been replaced by trolleybuses built new, in Mexico, by Mexicana de Autobuses SA (MASA) or its successor, Volvo.

[6] After May 1979, the only streetcar line still in operation was that from Tasqueña metro station to Xochimilco (route 54) and its short branch to Tlalpan (53).

[11] An expansion program implemented after 1982 raised the number of separate routes back to 27, operated by 30 different services,[8] by the end of 1988.

[18] STE's network reached its widest geographic coverage at that point, when the route most-distant from the city center was one from Tláhuac to Milpa Alta, in the far southeastern corner of the Federal District.

[2] On 1 August 2009, STE inaugurated its first Corredor Cero Emisiones, or Zero-Emissions Corridor, in which all public transport service along one of the city's major traffic arteries is now provided by electric trolleybuses.

[20][21] The Eje Central corridor alone now uses about 90–100 trolleybuses at peak times, from a sub-fleet of 120 vehicles reserved for this route.

Changes to route S (Eje 2/2A Sur) to transform it into a second Zero-Emissions Corridor took place in 2010, and the improved service was put into effect on 21 December 2010.

[24] The terminus is located in front of STE's main trolleybus depot, which also houses a small museum preserving one of the first electric trams to run in the city, as well as PCC car 2784 and some other historic material and documents.

[2] A third garage, El Rosario, opened in December 1998,[27] as a replacement for a much smaller depot, Azcapotzalco, which had closed in May of that year.

[2] In 2021, STE began operating a gondola lift-type cable car service with two lines and 13 stations, known as Cablebús.