The Mexico City Metro is the largest and busiest heavy-rail rapid transit system in Mexico and second in North America, only behind the New York City Subway.

The first line opened on 4 September 1969 with of route and 16 stations. The system was last extended in 2015 and now comprises 12 lines, 195 stations, and just over of route. Ten lines use rubber-tired trains, a technology adopted in part because of Mexico City's unstable soils.

Of the system's 195 stations, 44 serve two or more lines as transfer stations, 115 are underground, 54 are at street-level and 26 are elevated.

Many stations are named after historical figures, places, and events in Mexican history. All lines operate daily from 5 a.m. to midnight.

Line 1: Observatorio – Pantitlán

Line 1's Chapultepec – Zaragoza section was the first of the system to be opened, on September 4, 1969. The line was brought to its current length on August 22, 1984 with its final extension from Zaragoza to Pantitlán.

Line 1 runs mostly in a shallow box-tunnel just a few meters below the street, except for its initial stretch from Observatorio to Tacubaya, where it starts at street-level and progressively goes down to a deep circular tunnel through Tacubaya, where the box-tunnel begins. Line 1 is served by MP-68, NM-83 and NE-92 trains, built in France, Mexico and Spain in 1968, 1983 and 1992, respectively.

Transfer with other Metro lines is available at Tacubaya (lines 7 & 9), Balderas (line 3), Salto del Agua (Line 8), Pino Suárez (line 2), Candelaria (line 4), San Lázaro (line B) and Pantitlán (lines 5, 9 & A). Transfer to the Metrobús bus rapid transit (BRT) system is available at Tacubaya (line 2), Insurgentes (line 1), Cuauhtémoc (line 3), Balderas (line 3), Pino Suárez (line 4) and San Lázaro (lines 4 & 5).

Line 2: Cuatro Caminos – Tasqueña

Line 2 was the second line in the system to open, in 1970. After two expansions, the line has 24 stations, (the most number of stations on a line in the entire metro network), over a total track length of , of which are passenger track. The line has a general northwest–south direction passing through the city center and its color is blue. It starts at the border of the Federal District and the State of Mexico and ends in the city south.

It commutes with line 7 at Tacuba, line 3 at Hidalgo, line 8 at Bellas Artes, line 1 at Pino Suárez, lines 8 and 9 at Chabacano and line 12 at Ermita. At Tasqueña it links with the Mexico City Light Rail to Xochimilco. It used to be served by NC-82 and some NM-83 trains.

Line 2 was the scene of the worst accident in the Mexico City Metro's history on October 20, 1975, when a crash occurred between two trains at Viaducto Station. One train was parked at the station picking up passengers when it was hit by another train that did not stop in time. Twenty people were killed and several wounded. After that accident, automatic traffic lights were installed in all the lines.

Thirteen stations run underground while the remaining ten are surface stations. The line is currently served by NM-02 trains built in Mexico in 2004.

Line 3: Indios Verdes – Universidad

The first section of line 3 was opened in 1970. It has been expanded five times to comprise 21 stations over a total track length of , of which are passenger track, making it the second longest of the system. The line has a general north–south direction passing through the western end of downtown Mexico City and its color is olive green.

It is built under Insurgentes, Guerrero, Zarco, Balderas, Cuauhtémoc, Universidad, Copilco and Delfín Madrigal avenues. It commutes with line 6 at Deportivo 18 de Marzo, line 5 at La Raza, line B at Guerrero, line 2 at Hidalgo, line 1 at Balderas, line 9 at Centro Médico and line 12 at Zapata.

Most of the stations (17) run underground with the remaining four, including both terminals, being surface stations.

Line 3 Line color olive green Terminus Indios Verdes Universidad Passenger railway length 21.278 km Total railway length 23.609 kmRolling stock NM-79 trains made in Mexico in 1979 Stations 21 Type of line Universidad is a superficial terminal. From Copilco to La Raza, underground. From Potrero to Indios Verdes, combines superficial platforms with underground passenger passages. Direction North-South, through the city center Started operations November 20, 1970: from Tlatelolco to Hospital General August 25, 1978: from Tlatelolco to La Raza December 1, 1979: from La Raza to Indios Verdes June 7, 1980: from Hospital General to Centro Médico August 25, 1980: from Centro Médico to Zapata August 30, 1983: from Zapata to Universidad

Line 4: Santa Anita – Martín Carrera

The first section of line 4 was opened in 1981, and it was expanded once to bring the total extension of this line to ten stations over of track, of which are passenger track. The line has a general north–south direction and is located east of the city center and its color is aqua. It is also the line with the lowest passenger flow, which is why the STC introduced modified 6-wagon trains. In the original blueprint, this line was planned to extend to the north all the way to Ecatepec, Mexico State.

Line 4 is the only one in the system that does not have underground sections. Eight of the ten stations are built on an elevated viaduct and the remaining two are surface stations.

Line 4 connects with line 1 at Candelaria, line 6 at Martín Carrera, line 5 at Consulado, line 8 at Santa Anita, line 9 at Jamaica and line B at Morelos.

Line 4 Line color aqua Terminus Martín Carrera Santa Anita Passenger railway length 9.363 km Total railway length 10.747 km Rolling stock Six-wagon trains built in Spain by C.A.F. Stations 10 Type of line 8 elevated viaduct stations and 2 surface stations Direction North-South, on the east side of the city Started operations August 29, 1981: from Martín Carrera to Candelaria May 26, 1982: from Candelaria to Santa Anita

Line 5: Politécnico – Pantitlán

The first section of line 5 was opened in 1981, and it has been expanded twice to bring the total extension of this line to 13 stations over of track, of which are passenger track. The line has a general north-west to south-east direction relative to the city center and its color is yellow. This line previously had the NM73 trains but due to the introduction of the NM-02 trains in Line 2 now it is served by NC-82 Canadian trains made by Bombardier. Line 5 runs to Mexico City International Airport (Terminal Aérea station).

Line 5 has four underground and nine surface stations. Five stations connect with other metro lines. Line 5 Line color yellow Terminus Politécnico PantitlánRolling stock NC-82 trains made in Canada in 1982 Passenger railway length 14.435 km Total railway length 15.675 km Stations 13 Type of line From Politécnico to La Raza, superficial with underground access.Misterios and Valle Gómez, underground.From Consulado to Oceanía, superficial with underground accessTerminal Aérea and Hangares, underground and Pantitlán is superficial. Direction Northwest-Southeast Started operations December 19, 1981: from Pantitlán to Consulado July 1, 1982: from Consulado to La Raza August 30, 1982: from La Raza to Politécnico

Line 6: El Rosario – Martín Carrera

Line 6 had its first section inaugurated in 1983. It has been expanded once to bring the total extension of the line to 11 stations over of track, of which are passenger track. This line has a west–east direction running north of the city center and its color is scarlet red.

The line has only one surface station, the El Rosario terminal, while the rest of the line runs underground. Four stations connect with other metro lines. Line 6, like line 4, is also served by customized six-car trains.

Line 6 Line color red Terminus El Rosario Martín Carrera Passenger railway length 11.434 km Total railway length 13.947 km Rolling stock due to the low volume of persons in the line, the STC introduced six-wagon trains Stations 11 Type of line El Rosario is a superficial terminal. From Tezozomoc to Martín Carrera, underground. Direction West-East, in the city north Started operations December 21, 1983: from El Rosario to Instituto del Petróleo July 8, 1986: from Instituto del Petróleo to Martín Carrera

Line 7: El Rosario – Barranca del Muerto

The first section of line 7 was opened to the public in 1984. It has been expanded three times to bring the total length of the line to 14 stations over of track, of which are passenger track. Line 7 has a north–south direction running west of the city center and its color is orange.

The line has its only surface station in the El Rosario terminal. The rest of the line runs underground, with some sections being located more than 20 m below street level, making it the deepest line in the system at a maximum of 36 meters. Three stations connect with other metro lines.

This line used MP-68 trains and a small number of NM-73, after the rehabilitation of some MP-68. They kept circulating on this line although there is a slightly bigger number of NM-79 and NM-83 in this line. Today there are only retro adapted NM-73 and NM-83 models and some trains from the first model due to the introduction of the NM-02 in the Line 2. Currently the MP-68 trains from Line 9 are being reintroduced.

Line 7 Line color orange Terminus El Rosario Barranca del Muerto Passenger railway length 17.011 km Total railway length 18.784 km Stations 14 Type of line El Rosario is a surface terminal. From Aquiles Serdán to Barranca del Muerto, stations are underground. Direction North-South, at the city west Started operations December 20, 1984: from Tacuba to Auditorio August 22, 1985: from Auditorio to Tacubaya December 19, 1985: from Tacubaya to Barranca December 29, 1988: from Tacuba to El Rosario

Line 8: Garibaldi / Lagunilla – Constitución de 1917

Line 8 was the next to last route of the network to be opened, on July 20, 1994 by then President Carlos Salinas de Gortari and then regent of the city, Manuel Aguilera Gómez. Construction plans for the line date back to much earlier, but they were put on hold due to significant redevelopment. It has 19 stations over a total track length of , of which are passenger track. Line 8 runs in a general south-east direction, beginning near the city center, and its color is bright green. The line has 14 underground stations and five surface stations, including the southern terminal Constitución de 1917. Six stations connect line 8 with other metro lines. According to the Sistema de Transporte Colectivo, the volume of people moved in this line was 117,386,342 persons in 2006.

Line 8 Line color Green Terminus Garibaldi/Lagunilla Constitución de 1917 Passenger railway length 16.679 km Total railway length: 20.078 kmRolling stockMP-82 trains made in France between 1982 and 1984 Stations 19 Direction Center-Southeast Started operations July 20, 1994

Line 9: Tacubaya – Pantitlán

The first section of line 9 was opened to the public in 1987. It has been expanded once to a length of 12 stations over of track, of which are passenger track. The line was opened to relieve passenger traffic from line 1, to which it runs parallel south of the city center. The color of the line is dark brown.

Line 9 has eight underground stations with the remaining being elevated stations similar to those in line 4, including the terminal Pantitlán. It is the only line in the system in which no section of the track runs at street-level. Additionally, five stations connect with other metro lines. The trains of this line are made up from MP68 trains rehabilitated with fans and intelligent control systems and some NM-79 rolling stock.

Some of the stations were the set for the 1990 film Total Recall.