the glyph of Tláhuac. Symbol that represents said mayor's office. |} Extension A possible extension of the line to connect it with Line 1 at Observatorio station was announced in February 2013, thus making Observatorio the new west terminus of the line. The project was approved in September 2013 by Gerardo Ruiz Esparza, Secretary of Communications and Transportation. Construction started on 29 November 2017. The extension was expected to be completed by 2020, but works were delayed, thus, being projected to open by 2021. In September 2020, it was announced that works on Line 12 will be finished by the end of 2022 and that service will begin in 2023. The stretch will have three underground stations: Álvaro Obregón, Valentín Campa and Observatorio, in the Álvaro Obregón borough. Ridership According to the data provided by the authorities, the line registered 134,900,367 entrances, averaging 369,590 commuters per day in 2019. Tláhuac is the busiest station on the line—and one of the busiest of the system—averaging 56,831 entrances that year; in contrast Tlaltenco station averaged fewer than 5,000 passengers per year and consistently ranks among the least used on the Metro network. See also List of Mexico City Metro lines Notes References External links 2012 establishments in Mexico Railway lines opened in 2012 12