Westchester is a village in Cook County, Illinois, United States. It is a western suburb of Chicago. The population was 16,892 at the 2020 census.

The Blue Line is a 26.93-mile-long (43.34 km) Chicago "L" line which extends through The Loop from O'Hare International Airport at the far northwest end of the city, through downtown via the Milwaukee–Dearborn subway and across the West Side to its southwest end at Forest Park, with a total of 33 stations. At about 27 miles, it is the longest line on the Chicago "L" system and second busiest, and one of the longest local subway/elevated lines in the world. It has an average of 64,978 passengers boarding each weekday in 2022.