Resources > Glossary of U.S. Postal Units
Post Office Classifications
[Independent] Post Office
A 'regular' post office, with its own Postmaster, also known as a main post office or associate office—because it is an associate of its regional Processing & Distribution operation.

POStPlan, a cost-cutting program implemented during the 2010s, reorganized predominantly rural post offices into Administrative Post Offices (APOs), Remotely Managed Post Offices (RMPOs), and Part Time Post Offices (PTPOs). RMPOs are reduced-hour post offices (open 2, 4, or 6 hours per weekday) overseen by a Postmaster at a nearby Administrative Post Office. PTPOs are 6-hour post offices, with Postmasters, that are geographically removed from other post offices and are overseen by its postal District (see Districts, below). RMPOs do not have Postmasters of their own.

Nashville, Tennessee: South Station post office
A subordinate postal facility under the administration of a local Post Office and Postmaster, located within the corporate limits of the municipality for which the main post office is named.
Roanoke, Virginia: Hollins Branch post office
This branch of the Roanoke, Virginia Post Office lies in the town of Hollins.
A subordinate postal facility under the administration of a local Post Office and Postmaster, located beyond the corporate limits of the municipality for which the main post office is named.
  • The differentiation between station and branch is not always strictly adhered to.
  • Stations and branches can be either classified or contract.
Classified, or 'regular', operations are staffed by USPS employees.

Contract offices are operated under a contract with a private entity and staffed by non-USPS personnel, typically as part of another business. Such units provide only retail services; they do not conduct delivery or other postal operations.

→ In many postal listings, including the PMCC's Post Office Directory, a classified station is commonly abbreviated Sx; classified branch Bx; contract station S and contract branch B.
Contract Postal Unit (CPU)
Express Lube and Car Wash CPU
The Express Lube and Car Wash CPU is a contract station in Brunswick, GA.
The term CPU encompasses each of the terms: contract station; contract branch; and Community Post Office (CPO; see below).
Community Post Office (CPO)
CPO does not stand for Contract Post Office! It is short for Community Post Office. A CPO is a form / subset of CPU, generally in a rural area, which has replaced a closed independent post office. CPOs represent the only postal retail operations in their communities. The term CPO replaced those of Rural Station and Rural Branch in the 1970s.

→ All CPOs are CPUs; not all CPUs are CPOs.
Village Post Office (VPO)
A term for a new category of limited postal outlet; like CPOs, they are generally a replacement for a closed rural post office, though in some regions they are used to augment rural post offices whose hours have been reduced. Some VPOs have even opened in urban settings, beyond their original intention.

VPOs offer a bare minimum of services: they can sell stamps and feature a display of Flat-Rate packaging, but generally nothing more.

The first VPO opened in August 2011 in Malone, Washington. VPOs do not possess their own postmarks.

Distinct Mail Handling Operations
Carrier Annex
A form of classified station or branch which houses mail carriers but no retail operations. One might include customer package pick-up windows, but are otherwise generally closed to the public. Similar terms include Delivery Distribution Center (DDC); Parcel Post Annex; and Detached Carrier Unit (DCU). A new category of facility, the Sorting & Distribution Center (S&DC), is a regional hub for carriers that services multiple ZIP codes.

Connecticut's Guilford/Madison Carrier Annex
The Guilford/Madison Carrier Annex in Connecticut serves both towns.
Processing & Distribution Center / Facility (P&DC / P&DF)
A regional mail processing plant. Processing refers to outgoing mail, gathering of mail sent from post offices across the region, cancelling of stamps, sorting according to destination and dispatch; Distribution refers to incoming mail, receiving of mail from other areas, and distributing it to the local delivery offices in the region.

Philadelphia P&DC
Philadelphia's $272 million, 910,000-square-foot P&DC was 'activated' in 2006.

Generally, the primary distinction between a P&DC and P&DF is that a P&DC is larger.

As of 2023 USPS is implementing a plan to consolidate outgoing mail processing operations into a new class of facility called a Regional Processing & Distribution Center (RPDC). Another new class of facility, the Local Processing Center (LPC), is responsible for the distribution of mail to distribution units in an area.

Administrative Units
USPS Headquarters at L'Enfant Plaza
USPS Headquarters at L'Enfant Plaza
USPS Headquarters (L'Enfant Plaza)
This is the administrative heart of USPS, located at 475 L'Enfant Plaza, SW in Washington, DC. However, many of the management functions are done at lower levels.
As of a 2021 Postal Service reorganization the country is divided into four Areas: Atlantic, Central, Southern, and Western Pacific, with each further divided into 12 or 13 Districts. According to the USPS Office of the Inspector General, "area offices ensure headquarters directives are implemented."
This level of management is responsible for most day-to-day management duties for local post offices, including "customer service activities other than processing and distribution" (OIG). As of a 2021 reorganization there are 50 Districts, down from 67.

Photos are from the Evan Kalish collection.