INFORMATIONAL - Federal Ballot Mail Rule for 2026

Z4 Info File

A downloadable ZIP file containing information related to the Z4 Info File

Early Warning System (EWS002C0.ZIP)

This file is the EWS production file and is updated weekly. This file contains the Early Warning System data file for the CASS™ and MASS™ certification process.

INFORMATIONAL - UPDATE - Manifest Quality (MQ) Noncompliance

Known Issues List 9.15.2026

USPS APIs Release Notes

For the latest updates, please review the USPS APIs Release Notes.

USPS® Post Office and Blue Collection Box Location Dataset Briefing Sheet

Occupancy Trends License Agreement

USPS Population Mobility Trends License Agreement (Sample Only)

Population Mobility Trends Order Form

United States Postal Service Post Office™ and Collection Box Products Data License Agreement

Post Office™ and Collection Box Products Order Form

DELIVERY - Janesville Post Office (56048) - Temporarily Closed

September 2026 PCC Events Calendar

Mailers Technical Advisory Committee (MTAC): Association Membership Form

Merchant Onboarding and Authorization Tech Guide

Merchants need to follow a two-step process to authorize a Label Provider to generate shipping labels on their behalf.

1.   Log in or create a USPS business account on the Customer Onboarding Portal (COP) to get Customer Registration ID (CRID), Mailer ID (MID), and Enterprise Payment Account (EPA). A CRID is a unique identifier for your company. A MID is another identifier which can be part of the barcode on a piece of mail.
2.   Authorize Label Provider in COP. Before the merchant’s account can be used by Label Provider, Label Provider must be authorized. This will also enable Label Provider to generate package labels on behalf of NSA Holders at their NSA rates.
 

PROCESSING AND DISTRIBUTION - Central Processing Region - Louisville, KY Processing and Distribution Center (P&DC) Delays

PCC Events (September 2026)

INFORMATIONAL - New USPS NCOA API – Launching October 4, 2026

September 20, 2026 - FAST R69.0.1.0 Release Notes

September 20 2026 Time Limited Price Change (TLPC) 2026 [October] Release Notes

***Updated - New Areas*** - Area District 5-digit ZIP Codes (AREADIST_ZIP5.TXT)

City/State ZIP Code Weekly Compare

3 Digit ZIP/AISU Office List (AISUREPT.TXT)

Cumulative Listing of ZIP Codes Covered by the LACS Database

This document provides a cumulative listing of ZIP Codes covered by the LACS database for LACS^Link®.