When flying with United Airlines, how your checked bags are handled during a layover depends on whether your trip is domestic or international and if it's on a "single ticket." On a standard domestic itinerary within the U.S., your bags are automatically "tagged through" to your final destination; you do not need to collect them at your layover airport. However, if you have an international connection that involves entering the U.S. (e.g., London to JFK to San Francisco), you must collect your bags at the first point of entry, clear Customs, and then place them on the "Baggage Re-check" belt immediately outside the customs hall. For international connections outside the U.S. (e.g., Newark to Frankfurt to Delhi), United typically tags them through to the end, provided the connecting flight is with a Star Alliance partner like Lufthansa. In 2026, you can track your bag's real-time location via the United app, which will confirm if your bag has been successfully scanned onto your connecting aircraft during the layover.