Naics 2012 Industry Definition 491 - Postal Service The Postal Service subsector includes the activities of the National Post Office and its subcontractors in delivering letters and small parcels, normally without pick-up at the senders' location. These articles can be described as those that can be handled by one person without using special equipment. This allows the collection, pick-up, and delivery operations to be done with limited labor costs and minimal equipment. Sorting and transportation activities, where necessary, are generally mechanized. The restriction to small parcels distinguishes these establishments from those in the transportation industries. The traditional activity of the National Postal Service is described in this subsector. Subcontractors include rural Post Offices on contract to the Postal Service. Bulk transportation of mail on contract to the Postal Service is not included here, because it is usually done by transportation establishments that carry other customers' cargo as well.