Connecting at Houston: two ways between terminals, one behind security

Last checked 29 September 2026

At Houston, United's Texas hub, there are two separate ways to move between the five terminals, and only one of them keeps you behind security. Picking the right one matters more here than the airline you're flying.

At a glance

• The Skyway is behind security: an automated train linking Terminals A, B, C and D/E every 2 minutes. This is the one for a domestic-to-domestic connection.
• The Subway is a separate, older train that runs before security, linking A, B, C, D/E and the Airport Marriott. Useful for reaching the hotel or landside areas.
• Arriving from abroad, connecting onward: you'll clear immigration and customs at Terminal E, then recheck your bags and go through TSA security again before your next gate. IAH's own site recommends 90 minutes to 2 hours for this.
• IAH's passport-control wait: half of passengers were through within 16 minutes; one passenger in ten waited about 44 minutes or more (GateCast estimate from US Customs and Border Protection wait data, Sep 2025 to Sep 2026).
• United runs an automated tool that can hold a departing flight for passengers connecting from a delayed inbound one, at Houston among its other hubs. It isn't guaranteed. Worth knowing about if your inbound is United and running late.

Two trains, one behind security

The airport says international and long-haul flights often operate from Terminals D and E, with customs and immigration in Terminal E. Travel websites report that Terminal E is used only by United; check your boarding pass for your terminal. For Terminals A, B and C, sources don't fully agree on which airlines use which, so check your boarding pass before you assume.

What sets IAH apart from most hubs is having two separate ways to move between terminals. The Skyway is the one that matters for a connection: it's behind security, running every 2 minutes between stations in Terminals A, B, C and D/E. The Subway runs underground on the landside of security — useful for reaching the Airport Marriott or ground transportation.

Arriving internationally

Follow these steps in order.

1. Everyone arriving from abroad: international arrivals come in through Terminal E. Clear immigration, either with an officer or at a Global Entry kiosk.
2. Everyone: collect your bags on the level below, then go through customs.
3. If you're connecting onward: head to the recheck counters and recheck your bags.
4. If you're connecting onward: go through TSA security screening again, at a checkpoint built specifically for international connections. Houston Airports says this takes under 20 minutes, with a PreCheck lane available.

IAH's own site recommends allowing 90 minutes to 2 hours for this whole process on a connection.

Passport control at IAH: half of passengers were through within 16 minutes; one passenger in ten waited about 44 minutes or more (GateCast estimate from US Customs and Border Protection wait data, Sep 2025 to Sep 2026).

If your first flight is delayed

United operates an automated system, active at Houston among its other US hubs, that can hold a departing flight for passengers connecting from a delayed inbound United flight. This isn't guaranteed, and GateCast's grades don't currently account for it. Worth knowing it exists if your first leg is United and running late.

Tips

• Know which train you need before you land: Skyway if you're moving between flights, Subway if you're headed to the hotel or landside.
• Landing internationally, budget the airport's own suggested 90 minutes to 2 hours, on top of whatever the passport-control queue looks like that day.
• Travel websites report that Terminal E handles both international and domestic United flights. If that holds for your flights, an international arrival connecting to another United flight may not need to change terminals, just recheck bags and clear security again. Check your boarding pass.

Checked 29 September 2026. Terminals and procedures change, so confirm with the airport and your airline before you travel.

Book hotels near IAH Sponsored