structural:expansion, quality:correction
The Mexico City Metro is a rapid transit system that serves the metropolitan area of Mexico City, including some municipalities in the State of Mexico. Operated by the Sistema de Transporte Colectivo (STC), it is the second largest metro system in North America after the New York City Subway. The inaugural STC Metro line was 12.7 kilometres (7.9 mi) long, serving 16 stations, and opened to the public on 4 September 1969. The system has expanded since then in a series of fits and starts. As of 2015, the system has 12 lines, serving 195 stations, and 226.49 kilometres (140.73 mi) of route. Ten of the lines are rubber-tired. Instead of traditional steel wheels, they use pneumatic traction, which is quieter and rides smoother in Mexico City's unstable soils. The system survived the 1985 Mexico City earthquake. Of the STC Metro's 195 stations, 44 serve two or more lines. Many stations are named for historical figures, places, or events in Mexican history. It has 115 underground stations; 54 surface stations and 26 elevated stations. All lines operate from 5 a.m. to midnight. At the end of 2007, the Federal District government announced the construction of the most recent STC Metro line, Line 12, which was built to run approximately 26 kilometres (16 mi) towards the southeastern part of the city, connecting with Lines 7, 3, 2 and 8. This line opened on 30 October 2012.