High Quality Content by WIKIPEDIA articles! The Orange Line, is a rapid transit line in Chicago, Illinois run by the Chicago Transit Authority as part of the `L` system. It is approximately 12.5 miles (20.1 km) long (35-minute ride), and runs below grade and elevated on existing railroad embankments and new concrete and steel structures from Chicago Midway International Airport, the Southwest Side and downtown Chicago. In September 2012, the average weekday boardings on the Orange Line was 63,037.