Carrier Route
A specific path assigned to a USPS mail carrier within a ZIP code, covering a defined set of delivery points that the carrier visits in sequence.
Each standard ZIP code is divided into carrier routes, identified by a route type letter and a 3-digit number (e.g., C001 for city route 1, R003 for rural route 3). The USPS uses several route type codes: C (city), R (rural), H (highway contract), B (PO Box section), and G (general delivery).
Carrier routes typically contain 400-600 delivery points for city routes and may cover larger geographic areas with fewer stops for rural routes. Each weekday, the carrier sorts the mail for their route into delivery sequence (walk order) before departing.
Mailers who pre-sort by carrier route receive significant postage discounts. Carrier-route presort is one of the deepest discount levels, just above delivery-point sorting. The USPS periodically adjusts carrier route boundaries to balance workloads.