Chicago O'Hare Airport Terminal Transfer Guide: T1, T2, T3, and T5 ATS Train, Minimum Connection Times, and Baggage Rules (2026)

Quick Summary

• Primary Update: Chicago O'Hare International Airport (ORD) connects its four active passenger terminals—domestic Terminals 1, 2, and 3, and international Terminal 5—via the 24/7 automated Airport Transit System (ATS) people mover, supplemented by airside Terminal Transfer Buses (TTB) for eligible sterile transfers.
• Transit Impact: Terminal 5 is physically separated from Terminals 1, 2, and 3 across the airfield with no pedestrian walkway. All arriving international passengers must clear U.S. Customs and Border Protection (CBP), retrieve checked baggage, hand tagged luggage to airline re-check belts, and re-clear TSA security at their departing terminal.
• Traveler Advice: Single-ticket domestic-to-international transfers require 75 to 90 minutes; international-to-domestic transfers require at least 150 to 180 minutes (2.5 to 3.0 hours) to accommodate immigration queues, baggage retrieval, customs inspection, ATS transit, and TSA screening. Self-transfers on separate tickets require a minimum buffer of 3.5 to 4.0 hours.

Chicago O'Hare International Airport (ORD) operates as one of the world's most heavily trafficked mega-hubs, anchoring primary flight banks for United Airlines and American Airlines alongside dozens of foreign flag carriers. Spanning four active passenger terminals arranged across a vast airfield, O'Hare handles hundreds of thousands of connecting fliers weekly. Navigating an itinerary between domestic concourses and international gates requires a precise understanding of the airport's layout, transit vehicles, baggage re-check rules, and federal border procedures.

While domestic Terminals 1, 2, and 3 are clustered together and connected post-security, Terminal 5 sits completely isolated on the eastern side of the airfield. Understanding how and when to use the automated Airport Transit System (ATS) train versus secure airside buses is essential to avoiding missed connections.

          DOMESTIC CORE (AIRSIDE CONNECTED)                                ISOLATED INTERNATIONAL TERMINAL

[ TERMINAL 1 ] <--- Airside Bridge (5-8m) ---> [ TERMINAL 2 ]                               [ TERMINAL 5 ]
United Mainline,                               United Express,                              All Foreign Flag Carriers
Lufthansa (Dep),                               Alaska, JetBlue                              (Air India, Emirates,
ANA (Dep)                                            |                                      Qatar, BA, Lufthansa Arr),
      |                                              |                                      Delta, Southwest
      |                                    Airside Walkway (5-8m)                                 ^
      |                                              |                                            |
      |                                              v                                            |
      |                                        [ TERMINAL 3 ]                                     |
      |                                        American Airlines,                                 |
      |                                        Spirit, Iberia (Dep),                              |
      |                                        JAL (Dep)                                          |
      |                                              |                                            |
      +-----------------------+----------------------+--------------------------------------------+
                                                                                                  |
                              v
================== AIRPORT TRANSIT SYSTEM (ATS PEOPLE MOVER - 24/7 LANDSIDE) =========================================
[ ATS: Terminal 1 ] <--- 90s ---> [ ATS: Terminal 2 ] <--- 90s ---> [ ATS: Terminal 3 ] <--- 3-4m ---> [ ATS: T5 ]
======================================================================================================================

- - - - - - - - -  AIRSIDE TERMINAL TRANSFER BUS (TTB - TICKETED STERILE ONLY) - - - - - - - - - - - - - - - - - - -
Gate B1 (T1)  <=============================================================================>  Gate M13 (T5)
Gates G17 & K20 (T3) <=======================================================================>  Gate M13 (T5)

Terminal Assignments Across Chicago O'Hare

O'Hare designates four active passenger terminals numbered 1, 2, 3, and 5. (Terminal 4 was permanently decommissioned in 1993 following the opening of modern Terminal 5 and remains unassigned in O'Hare's terminal numbering system).

• Terminal 1 (Concourses B and C): Serves as United Airlines' flagship domestic and international hub. Concourse B connects to Concourse C via an underground pedestrian tunnel featuring moving walkways and Michael Hayden's iconic neon kinetic light sculpture. Select Star Alliance partners—including Lufthansa and All Nippon Airways (ANA)—use Terminal 1 for passenger check-in and departures, though their inbound international flights disembark at Terminal 5.
• Terminal 2 (Concourses E and F): Houses United Express regional operations, alongside Alaska Airlines and JetBlue. Concourse E and F gates connect seamlessly to Terminal 1 and Terminal 3 through post-security walkways.
• Terminal 3 (Concourses G, H, K, and L): Functions as American Airlines' primary midwest hub, serving mainline domestic routes, regional American Eagle services, and international departures. Spirit Airlines also operates out of Terminal 3 Concourse L. Select oneworld partners, such as Iberia and Japan Airlines (JAL), depart from Terminal 3 gates.
• Terminal 5 (Concourse M): The airport's dedicated international arrivals complex, housing U.S. Customs and Border Protection Federal Inspection Services (FIS). All foreign flag carriers—including Air India, Emirates, Qatar Airways, British Airways, Air France, KLM, Turkish Airlines, Etihad Airways, Korean Air, EVA Air, and SAS—arrive at Terminal 5. Following recent expansion, Terminal 5 also hosts Delta Air Lines (both domestic and international operations), Southwest Airlines, and Frontier Airlines.

Inter-Terminal Transit Systems: ATS Train vs. Airside Buses

Passengers transferring between gates at Chicago O'Hare have three distinct movement options depending on their ticketing, security status, and baggage requirements.

1. Airport Transit System (ATS People Mover)

The ATS is a fully automated, elevated people mover operating 24 hours a day along a 3-mile guideway. It provides the primary landside inter-terminal link between domestic Terminals 1, 2, and 3, international Terminal 5, and the Multi-Modal Facility (MMF / Rental Cars and Metra train station).

• Operating Hours: 24 hours daily, 365 days a year.
• Frequency: Trains depart every 3 to 5 minutes during peak hours (05:00 to 22:00) and every 5 to 10 minutes during overnight hours.
• Travel Time: 90 seconds between adjacent domestic stations (T1 to T2, or T2 to T3). The nonstop transit between Terminal 3 and Terminal 5 takes approximately 3 to 4 minutes. A complete ride from Terminal 1 to Terminal 5 requires roughly 6 to 8 minutes.
• Fare: Free of charge for all travelers; no tickets, transit cards, or boarding passes are required.
• Station Access: In Terminals 1, 2, and 3, ATS stations are located on the Upper/Departures level mezzanine, accessed via escalators and elevators from the check-in halls. At Terminal 5, the ATS station is located on Ground Level directly accessible from the terminal arrivals hall.
• Security Status: The ATS operates entirely landside (outside TSA security). Boarding the ATS requires exiting the secure airside concourses; passengers must pass through TSA security checkpoint screening at their connecting terminal.

2. Airside Terminal Transfer Bus (TTB)

For passengers arriving on domestic flights in Terminals 1 or 3 who are connecting to international flights departing from Terminal 5, the Chicago Department of Aviation operates the airside Terminal Transfer Bus (TTB).

• Purpose: Enables sterile, post-security transit to Terminal 5 without exiting through TSA exit lanes or waiting in landside security lines at Terminal 5.
• Eligibility: Travelers must already hold a valid outbound boarding pass departing from Terminal 5, and their checked baggage must already be checked through to their final destination.
• Pickup Locations:
  • Terminal 1: Airside bus gate located near Gate B1.
  • Terminal 3: Airside bus gates located near Gate G17 and Gate K20.
  • Terminal 5: Deboards airside at Gate M13.
• Operating Schedule: Operates daily from approximately 11:30 AM to 9:30 PM (hours adjust seasonally to match major international departure banks).
• Travel Time: 10 to 15 minutes including bus loading and airfield transit.

3. Airside Walking Network Between Terminals 1, 2, and 3

Passengers connecting exclusively between domestic flights on United, American, Alaska, or JetBlue can walk between Terminals 1, 2, and 3 without leaving the secure airside area:

• Terminal 1 to Terminal 2: An indoor post-security connector links Concourse B of Terminal 1 to Concourse E of Terminal 2. The walk takes 5 to 8 minutes.
• Terminal 2 to Terminal 3: A post-security corridor links Concourse F of Terminal 2 to Concourse G and H of Terminal 3. Walking takes 5 to 8 minutes.
• Terminal 1 to Terminal 3: Transiting across the entire domestic complex from Concourse C/B to Concourse K/L takes 12 to 18 minutes.
• Terminal 5 Exception: Terminal 5 is physically separated from Terminals 1, 2, and 3 across taxiways. There is no pedestrian walkway connecting Terminal 5 to any other terminal.

Minimum Connection Times (MCT) at O'Hare

Airlines establish Minimum Connection Times (MCT) representing the tightest allowable scheduled layovers for valid through-tickets. Booking an itinerary below these parameters voids misconnect protections.

International Arrival Logistics: CBP Clearance and Baggage Re-Check

The United States does not offer sterile international transit facilities. Every passenger disembarking from a foreign flight at O'Hare Terminal 5 enters United States legal jurisdiction and must complete federal border clearance procedures, even if their onward destination is a foreign country.

Baggage Re-Check Protocols

1. Single-Ticket / Interline Bookings: If your itinerary was booked under a single reservation with through-ticketing (such as Air India connecting to United, or British Airways connecting to American), your baggage tag already displays your final destination airport code. After collecting your bags in the Terminal 5 customs hall and clearing the final inspection booth, look immediately outside the exit doors. Dedicated baggage re-check desks for United Airlines, American Airlines, and Delta Air Lines are staffed directly in the arrivals lobby. Hand your luggage to the airline agent. They will scan your tag, confirm your flight connection in the system, and place your bags on the inter-terminal transfer belt. You do not pay additional checked baggage fees.
2. Separate-Ticket / Self-Transfer Bookings: If you purchased two independent tickets—for example, arriving on an international carrier and holding a separately booked ticket on United, American, or Southwest—the Terminal 5 baggage transfer desks will not accept your bags. You must load your luggage onto a cart, take the elevator to the ATS train, transport your luggage to your departure terminal (Terminal 1, 2, or 3), and check in at the main ticketing counters. You must complete this check-in and bag drop before the airline's standard 45-to-60-minute domestic cutoff window.

Traveler Logistics Guide

Navigating transfers efficiently requires executing specific maneuvers based on your inbound gate and connecting airline.

Step-by-Step Connection Checklists

Scenario A: Arriving Internationally at Terminal 5, Connecting Domestically to United (T1) or American (T3)

• Time Allocated: Minimum 2.5 to 3.0 hours.
• Step 1: Exit the aircraft and walk along the elevated international arrival corridor directly into the CBP Federal Inspection Services hall. Eligible travelers should use the Mobile Passport Control (MPC) app to access expedited lanes.
• Step 2: After passport inspection, proceed down to the baggage claim area and retrieve all checked bags from your flight's assigned carousel.
• Step 3: Exit through the customs agricultural inspection checkpoints.
• Step 4: Immediately outside the customs exit doors, hand your tagged luggage to the United Airlines (left) or American Airlines (right) re-check counter.
• Step 5: Follow signs to the Airport Transit System (ATS) station inside Terminal 5. Take the elevator/escalator up to the platform.
• Step 6: Board the next inbound ATS train toward Terminals 1, 2, and 3. Disembark at Terminal 1 for United flights or Terminal 3 for American flights (travel time: 4 to 6 minutes).
• Step 7: Enter the TSA security screening checkpoint at your departure terminal.
• Step 8: Locate your departure gate on the flight information display monitors. If departing from United Concourse C in Terminal 1, use the underground tunnel beneath Concourse B (allow 7 to 10 minutes walking time).

Scenario B: Arriving Domestically at Terminal 1 or Terminal 3, Connecting to International Flight at Terminal 5

• Time Allocated: Minimum 75 to 90 minutes.
• Step 1: Disembark your domestic flight. Because your luggage is checked through to your overseas destination, you do not need to claim bags.
• Step 2: Check your onward flight departure time and gate assignment:
  • Option 1 (Airside Bus - Recommended if operational): If transferring between 11:30 AM and 9:30 PM and you already hold a boarding pass for Terminal 5, proceed to Gate B1 in Terminal 1 or Gate G17 / K20 in Terminal 3. Board the Terminal Transfer Bus directly to Gate M13 at Terminal 5. This avoids clearing TSA security again.
  • Option 2 (Landside ATS Train): Exit through the secure exit doors to the landside ticketing lobby. Follow signs to the ATS station on the departures mezzanine. Board the train to Terminal 5 (3 to 6 minutes). Proceed to Terminal 5 TSA security screening on the upper level, clear screening, and walk to your departure gate.

Frequently Asked Questions

Can I walk between Terminal 5 and domestic Terminals 1, 2, or 3 at O'Hare?

No. Terminal 5 is physically isolated across active taxiways and runways on the eastern side of the airport campus. There are no pedestrian walkways, skybridges, or underground tunnels connecting Terminal 5 to Terminals 1, 2, or 3. Travelers transferring between Terminal 5 and the domestic terminals must ride either the automated landside Airport Transit System (ATS) train or the secure airside Terminal Transfer Bus (TTB).

Do I have to collect my luggage during an international layover at Chicago O'Hare?

Yes. Under United States federal border regulations, all passengers arriving on flights from abroad must collect all checked baggage from the arrival carousels in the Terminal 5 customs hall, regardless of whether the bags are tagged through to an onward U.S. or international destination. After clearing customs, passengers traveling on a single through-ticket can immediately surrender their luggage at the dedicated airline transfer re-check desks located right outside the customs exit doors in Terminal 5.

Is the O'Hare Airport Transit System (ATS) train free to ride?

Yes. The Airport Transit System is completely free of charge for all travelers, visitors, and airport personnel. No ticket, transit pass, or boarding pass is required to enter the ATS stations or board the trains. The system operates 24 hours a day, 7 days a week, connecting Terminals 1, 2, 3, 5, and the Multi-Modal Facility (MMF).

How do I use the airside Terminal Transfer Bus to avoid re-clearing security at Terminal 5?

The airside Terminal Transfer Bus (TTB) operates between domestic Terminals 1 and 3 and international Terminal 5. To use the bus, you must already hold a valid onward boarding pass departing from Terminal 5, have your baggage checked through, and board during service hours (typically 11:30 AM to 9:30 PM). Bus pickup points are located airside at Gate B1 in Terminal 1 and at Gates G17 and K20 in Terminal 3. The bus transports fliers directly to Gate M13 inside the secure zone of Terminal 5, allowing you to bypass landside TSA security queues.