19 CFR § 122.101 - Entry of accompanied baggage.

Passengers who enter the U.S. on one aircraft and depart to a foreign area on another aircraft with accompanying baggage shall either:

(a) Submit their baggage to Customs for inspection; or

(b) Arrange with the importing carrier for the baggage to be processed under regular in-transit procedures.

When passengers choose not to have access to their baggage while in the U.S., the baggage shall be listed on the Air Cargo Manifest as provided in § 122.48.