Forest Park is a village in Cook County, Illinois, United States, and a suburb of Chicago. The population was 14,339 at the 2020 census. The Forest Park terminal on the CTA Blue Line is the line's western terminus, located on the Eisenhower Expressway at Des Plaines Avenue. This makes it one of just two municipalities served by the Chicago "L" train network that does not directly border Chicago.

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.