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.

Undeliverable-as-Addressed (UAA) Statistics by Mailing Industry Quarterly Report (Q3 FY25)

ACS Nixie stats by industry for FY25 Q3.

June 2025 Nixie Volume

This spreadsheet contains the UAA statistics for June 2025.

ZIP Codes by Area and District codes

The Excel spreadsheet lists ZIP Codes with the associated Area and District Codes.  

Pending Route Adjustment File

This Excel sheet details route adjustments for May 2025 thru August 2025.

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

Automated Zone Indicator (AZI) Table

The AZI table lists each five-digit ZIP Code™ and is an indicator of the type of processing that typically takes place on letter mail destined for each ZIP Code. Each number in the file is a ZIP Code appended with a numeric zone indicator. The five numeric indicators are as follows:

1. Two Pass Zones: Automated two-step sector/segment at mail processing facilities
2. 876 Carrier Route Sort Zones: Automated incoming secondary carrier route sorting at plants
3. Carrier Route Barcode Sorter (CSBCS) Zones: Automated walk sequence sorting on CSBCS machines at delivery units
4. Delivery Barcode Sorter (DBCS) Zones: Automated walk sequence sorting on DBCS machines at plants [i.e., sectional center facilities (SCFs)] or at delivery units
5. Manual/Mechanized Zones: No automated sorting; no tracking code scans should be generated from facilities matched to these ZIP Codes

City/State ZIP Code Weekly Compare

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