The Blue Line, also known as the O'Hare-Congress Line and the West-Northwest Line, is a long Chicago "L" line which goes 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. It is the CTA's second busiest rail line, with an average of 186,796 passengers boarding each weekday in September 2012.