High Quality Content by WIKIPEDIA articles! The Blue Line consists of a 19.5-mile (31.4 km) (68-minute ride) long trunk line in the Chicago Transit Authority`s rapid transit system which extends through Chicago`s 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 (Congress). It is the CTA`s second busiest rail line, with an average of 186,796 passengers boarding each weekday. The route`s full length is 34.6 miles (55.7 km) with a total of 33 stations.