O'Hare International Airport is 17 miles northwest of the Loop. It's the headquarters for United Airlines and a hub for American. Most non-US airlines and international flights use Terminal 5 (except Lufthansa and flights from Canada). The domestic terminals are 1, 2 and 3. ATMs and currency exchanges are available throughout. Wi-fi costs $8 per day.
Airport Express shared-van service goes downtown for $32 per person. Vans run between 4am and 11:30pm; they leave every 15 minutes. It takes 60 minutes or more, depending on traffic and where your hotel is in the drop-off order. Look for ticket counters by baggage claim.
The airport has its own El train station on the Blue Line operated by the Chicago Transit Authority. Trains run 24/7 and cost $5. The station is a long walk from the flight terminals. Follow the signs to baggage claim, then ones that are variously marked as ‘Trains to City’ and 'CTA.’ Trains depart every 10 minutes or so and reach downtown in 40 minutes. Unless you are staying right in the Loop, you will likely have to transfer (or hail a taxi) to complete your journey.
Rides to the center take 30 minutes and cost around $50. Taxi queues can be lengthy, and the ride can take longer than the train, depending on traffic. Taxi stands are outside baggage claim at each terminal.
Chicago Midway Airport is 11 miles southwest of the Loop. It has three concourses: A, B and C. Southwest Airlines uses B; most other airlines go out of A. There's a currency exchange in A and ATMs throughout. Wi-fi costs $8 per day.
The Airport Express door-to-door shuttle goes downtown for $27. Vans run between 4am and 10:30pm. It takes approximately 50 minutes. Look for ticket counters by baggage claim.
Rides to the center take 20 minutes or longer (depending on traffic) and cost $35 to $40. Taxis queue outside the main entrance.
The airport has its own El train station on the Orange Line operated by the Chicago Transit Authority. Trains operate between 4am and 1am and cost $3. They depart every 10 minutes or so and reach downtown in 30 minutes. The station is a fairly long haul from the concourses. Follow the signs for ‘Trains to City’ and 'CTA.'