Shipment Control Number (U.S. Shipments)
A Shipment Control Number, often abreviated as SCN, is a unique number assigned to a shipment of goods entering the United States. It serves as a means of telling shipments apart for CBP, while simultaneously identifying the carrier transporting the goods. Shipment control numbers are mandatory for almost every type of shipment being transported to the United States by highway carrier.
A shipment control number consists of the carrier's SCAC, followed by a unique reference number assigned by the carrier. The unique reference must be between 4 and 12 characters, which can be either numbers or letters. The most common use of shipment control numbers by a highway carrier is in their use of the PAPS process, in which the shipment control numbers are usually referred to simply as PAPS numbers.
Once used, a shipment control number must not be reused for a period of at least 3 years. It is often best practice though to ensure that they are never reused, as reuse makes record keeping more difficult.