Line B runs from downtown Mexico City north towards the municipality of Ecatepec de Morelos.

[4] The first stretch of the line, from Buenavista to Villa de Aragón, was inaugurated on 15 December 1999 by Ernesto Zedillo, President of Mexico from 1994 to 2000, and Rosario Robles, Head of Government of the Federal District from 1991 to 2000.

The second section, from Villa de Aragón to Ciudad Azteca, was opened on 30 November 2000, six years after it was planned.

[14] Due to this, the line has a high rate of crime inside the stations and the trains, going from the presence of pickpockets and petty theft to armed robbery and sexual assault.

[14] In 2017, at least three violent robberies were reported, in which armed men entered the wagons and stripped the passengers out of their belongings.