O’Hare is easier once you stop thinking of it as one enormous building. Terminals 1, 2, and 3 form a connected domestic complex. Terminal 5 sits apart and handles many international flights along with some domestic service. Your operating airline and gate—not the logo that sold the ticket—tell you where to go.
A quick guide to the terminals
| Terminal | Concourses | What to expect |
|---|---|---|
| 1 | B and C | United’s main terminal, with some international departures by United and Star Alliance partners |
| 2 | E and F | A mix of United operations and other domestic flights |
| 3 | G, H, K, and L | American’s main terminal, plus several other carriers |
| 5 | M | Most international arrivals and many international departures, plus some domestic flights |
There is no Terminal 4. The numbering jumps from 3 to 5, so you haven’t missed a sign.
Airlines can use more than one terminal, especially for international service. A codeshare adds another wrinkle: the marketing airline on your confirmation may not operate the plane. Look for “operated by” on the itinerary, then confirm the live gate.
Making a connection at O’Hare
Between Terminals 1, 2, and 3
The domestic terminals connect on the secure side. Follow the overhead signs and walk to the next concourse; do not take the Airport Transit System for a normal connection between these terminals. The ATS is outside security, so using it would add another checkpoint.
A connection that looks short on the map can still be a long walk. B to C uses the underground tunnel in Terminal 1, while the far ends of the L and C concourses are well away from the central terminal buildings. Head toward the new gate before stopping for food.
Between Terminal 5 and the domestic terminals
O’Hare operates a secure-side Terminal Transfer Bus between Terminal 5 and pickup points in Terminals 1 and 3. The airport currently lists service every 15 minutes from 11:30 a.m. to 9:30 p.m., but operating hours and eligibility can change. You need a boarding pass, and the service may not fit every itinerary.
If the bus is unavailable, exit security and take the free ATS. It stops at Terminals 1, 2, 3, and 5, then continues to the Multi-Modal Facility. After changing terminals, you will go through security again.
After an international arrival
If your flight was not precleared before departure, you will normally clear U.S. immigration, collect all checked bags, pass customs, and recheck connecting baggage. Then follow signs to your departure terminal and TSA screening. A bag tagged to the final destination still usually has to be collected for customs at the first U.S. entry point.
Flights from certain airports complete U.S. preclearance before takeoff. Those arrivals are handled more like domestic flights. Your airline can tell you whether that applies to your route.
Starting a trip at O’Hare
- Confirm the operating airline. This prevents many wrong-terminal mistakes.
- Check the terminal and gate. Recheck on departure day and again on the way to the airport.
- Read the airline’s cutoff. Bag drop and check-in can close well before departure.
- Plan to boarding time. The door may close before the scheduled departure time.
Two hours before a domestic departure and three hours before an international departure are sensible starting points inside the correct terminal. Add time for a rental-car return, remote parking, checked bags, children, mobility needs, or a busy holiday. See the O’Hare TSA guide for a fuller security plan.
Getting around the airport
Airport Transit System
The ATS is O’Hare’s free landside train. It runs 24 hours a day and serves every terminal plus the Multi-Modal Facility, where you will find rental cars, Economy Lot F, Kiss ’n’ Fly, regional buses, Pace, and the O’Hare Transfer Metra station. The airport says trains arrive every three to five minutes at peak times and the ride from Terminal 1 to the MMF takes about ten minutes.
Because the ATS is outside security, it is useful for arriving passengers, people changing to Terminal 5 when the transfer bus is unavailable, and travelers going to rental cars or remote pickup. It is not the best route between domestic gates.
CTA Blue Line
The CTA Blue Line runs from O’Hare to downtown Chicago 24 hours a day. The station is connected by pedestrian routes to Terminals 1, 2, and 3. From Terminal 5, take the ATS to Terminal 2 and follow signs for “CTA Trains” or “Trains to City.” CTA lists a normal downtown trip at about 40 to 45 minutes.
Rental cars and remote pickup
On-airport rental-car companies are in the Multi-Modal Facility rather than at the terminal curb. Take the ATS to the final MMF stop. Kiss ’n’ Fly and Economy Lot F use the same stop.
If your flight is delayed
O’Hare weather can shift gates and connection times quickly. Keep the airline app’s notifications on, but also watch the departure screens and gate podium. During a delay, stay where you can return to the gate promptly; an estimated departure can move earlier.
If you will miss a connection, look for rebooking options in the airline app while you join the service line. Before leaving the airport or accepting a route through a different Chicago airport, ask what will happen to your checked bag.
A ground stop does not automatically mean your flight is canceled. It can hold O’Hare-bound aircraft at their origin while traffic is managed. Our O’Hare ground-stop guide explains how to read the notice and what to do next.
Frequently asked questions
Can you walk between terminals at O’Hare?
You can walk between Terminals 1, 2, and 3 after security. Terminal 5 is separate; use the eligible airside transfer bus when it is operating or exit security and take the ATS.
How long does it take to change terminals?
There is no reliable single time. A domestic walk may take 10 minutes or more than 30 depending on the gates. A Terminal 5 change can add a bus wait or an ATS ride plus another security line.
Why is there no Terminal 4?
O’Hare’s current passenger terminals are numbered 1, 2, 3, and 5. Terminal 4 was a temporary international facility that closed after Terminal 5 opened.
Is the O’Hare train between terminals free?
Yes. The Airport Transit System is free. The CTA Blue Line into Chicago requires a fare.
Terminal and transfer information reviewed July 16, 2026. Check your airline and FlyChicago on the day of travel.
Sources
- Chicago Department of Aviation: Connecting Traveler (accessed July 16, 2026)
- Chicago Department of Aviation: Transportation Between Terminals (accessed July 16, 2026)
- Chicago Department of Aviation: Airport Transit System (accessed July 16, 2026)
- Chicago Department of Aviation: International Travel (accessed July 16, 2026)
- Chicago Transit Authority: Airport trains (accessed July 16, 2026)
These links are here so you can check the details yourself. ARECO receives no payment when you use them.