Follow the airport signs to the CTA Orange Line/transit center. At the transit center, walk outside to the CTA bus terminal and board the #55 Garfield bus. The bus runs east on 55th Street to the Museum of Science and Industry. Exit at the Ellis Avenue stop (you will see the Ratner Atheletic Center on the corner). Walk south on Ellis Avenue towards the heart of campus.
Take the CTA Blue Line train from the airport to the Jackson stop downtown. Exit the subway and walk one block east to State Street. Then follow directions for travel by the #6 Jackson Park Express bus on the Mass Transit page.