The current rolling stock of the Chicago "L" rapid transit system consists of four series of railcars. The oldest series is the 2600-series which was built between 1981 and 1987 and refurbished between 1999 and 2002. The second series is the 3200-series, built between 1992 and 1994 and refurbished between 2015 and 2018. The third and newest series is known as the 5000-series; built between 2009 and 2015, they feature new technologies such as LED color signs, security cameras, new seating configuration, AC motors, and interior LED signs displaying date and time. The most recent order consists of the 7000-series cars that are planned to replace the 2600-series cars, with options for additional cars that would replace the 3200-series cars.

The Chicago "L" is the rapid transit system serving the city of Chicago and some of its surrounding suburbs in the U.S. state of Illinois. Operated by the Chicago Transit Authority (CTA), it is the fourth-largest rapid transit system in the United States in terms of total route length, at 102.8 miles (165.4 km) long as of 2014, and the third-busiest rapid transit system in the United States. In 2016, the "L" had 1,492 rail cars, eight different routes, and 145 train stations. In 2023, the system had 117,447,000 rides, or about 373,800 per weekday in the fourth quarter of 2023.