USPS® Unique ZIP Codes™ and Anchor’s Address-Hygiene Products
Unique ZIP Codes within the United States Postal Service can often be a confusing topic. To understand the
role of Unique ZIP codes within the USPS, and how they play their part within the process of address hygiene,
we will discuss the underlying concepts for Unique ZIP Codes and how they are represented within Anchor’s
products.
Unique ZIP Codes are special ZIP Codes that are assigned by the USPS to some type of institution, like a
governmental agency, or a large business, or a university. These institutions are large enough that they have
their own internal mail distribution system. The mail is not delivered within the institution by the USPS but is
instead collected by the USPS and delivered to the institution in bulk. It is then the responsibility of the
institution to deliver the mail internally to the various departments or individuals.
The USPS does not always maintain records in their databases for the individual deliveries within the Unique
ZIP Code. It is up to the institution whether or not they want to have their addresses stored within the USPS
data. Institutions are allowed to structure their addresses however they like, and sometimes this does not fall
within the standard parameters of a USPS-style address. As a result, in many cases, it is difficult or impossible
to know if an address is truly valid when it is inside of a Unique ZIP Code, just by looking at the USPS
databases.
When an institution chooses to do so, there will be records within the USPS ZIP+4 database for their Unique
ZIP Code. When these records exist, it is possible for address-hygiene software to match to them,
standardized the address, and return the appropriate ZIP+4 code. However, the USPS DPV database does not
contain any records for Unique ZIP Codes. As a rule, all addresses for a Unique ZIP code that are processed
through the USPS DPV database will return a 'yes' flag for the delivery indicator. The USPS DPV database, therefore, can not be used to determine if an address in a Unique ZIP Code is a valid delivery, because every
address submitted through address-hygiene software will return a DPV code of ‘yes.’
In cases where an institution does not choose to have any records in the USPS database, the USPS CASS
rules require that an input address be assigned a default ZIP+4 code. This default ZIP+4 code is always 0001.
There are also cases where an institution may choose to only have some of their addresses represented in the
USPS database, but not all of them. In such a situation, during an address-hygiene process, if an input
address is found in the USPS database, then it will be matched and the appropriate ZIP+4 code will be
returned. If the input address is not found in the database, then it will be returned with the default ZIP+4 code
of 0001. This can further be complicated by the fact that there may be an actual record in the ZIP+4 database
with a +4 code of 0001, but any other address for the Unique ZIP Code that is not in the database will also be
returned with that 0001 +4 code.
A collection of footnote codes exists within Anchor’s address-hygiene products to help identify when an
address falls under the different possible scenarios. These footnote codes are identified below:
U1 - Unique ZIP Code Match
This is the main footnote code that identifies when an address falls within a Unique ZIP Code. The USPS
requires that this footnote code be returned in a Unique ZIP Code situation during CASS processing. This
footnote code does not identify if the input address was matched to an actual record within the USPS
database, or if it was assigned a default ZIP+4 code because the address was not in the database.
A5 - Unique ZIP+4 Default Code Returned
This footnote indicates that the address for the Unique ZIP Code was not found within the USPS database,
and the default ZIP+4 code of 0001 was assigned.
Example:
USPS Database contains the following record for the Unique ZIP Code 12345:
1 River Rd / Schenectady NY 12345-6000
Input Address: 123 Main St / Schenectady NY 12345
Output Address: 123 Main St / Schenectady NY 12345-0001, Footnotes U1, A5, AU
Footnote A5 was returned because this address does not exist within the USPS database, and was
therefore given a default +4 code.
Input Address: 1 River Rd / Schenectady NY 12345
Output Address: 1 River Rd / Schenectady NY 12345-6000, Footnotes U1
Footnote A5 was not returned because this address does exist within the USPS database and the
ZIP+4 code from the database was assigned.
AU - Unique ZIP Default Information Returned
When an input address for a Unique ZIP Code does not exist within the USPS database, then the default +4
code of 0001 will be assigned. In this case, CASS rules require address-hygiene software to check to see if
there might be another record that is in the database that also has the 0001 footnote code. If there is no such
record, then this footnote is returned, indicating that the ZIP+4 database fields that are returned along with the
address where generated from default information This default ZIP+4 database fields include the Carrier Route
ID, and the record type code of the address.
Example:
USPS Database contains the following record for the Unique ZIP Code 12345:
1 River Rd / Schenectady NY 12345-6000
Input Address: 123 Main St / Schenectady NY 12345
Output Address: 123 Main St / Schenectady NY 12345-0001, Footnotes U1, A5, AU
Footnote AU was returned because there is no record in the database for 12345-0001, and so default
ZIP+4 information is returned.
In the opposite case, when a default +4 code of 0001 is assigned, and there is a different record in the USPS
database that also has the 0001 +4 code, then the footnote AU will not be returned. This indicates that the
information contained in the returned ZIP+4 database fields (Carrier Route ID, record type, etc.) came from an
actual 0001 database record, and does not represent default information.
Example:
USPS Database contains the following record for the Unique ZIP Code 38145:
PO BOX 388 / Memphis, TN 38145-0001
Input Address: 123 University St / Memphis, TN 38145
Output Address: 123 University St / Memphis, TN 38145-0001, Footnotes U1, A5
Footnote A5 was returned because “123 University St“ does not exist in the database and the default
ZIP+4 code was assigned. However, the ZIP+4 code of 38145-0001 does belong to another record (in
this case a PO BOX record), and therefore the returned ZIP+4 database fields (Carrier Route ID, record
type, etc.) contain information from the actual 0001 database record.
AQ - Unique ZIP Record Match that Returns Data from Input Addon
In many cases, an input address will contain a +4 code, most likely assigned from a previous address-hygiene
process. When an input address contains a +4 code, USPS CASS rules require that the input +4 code be used
when examining the records in the ZIP+4 database. If a record is found in the database that matches the input
address, but it does not match the input +4 code, then the input +4 code is retained in the output address, and
the ZIP+4 database-record fields from the input +4 code are returned.
Example:
USPS Database contains the following records for the Unique ZIP Code 38136:
PO BOX 361000 / Memphis, TN 38136-1000
1921 ELVIS PRESLEY BLVD / Memphis, TN 38136-6947
Input Address: 1921 Elvis Presley Blvd / Memphis, TN 38136-1000
Output Address: 1921 Elvis Presley Blvd / Memphis, TN 38136-1000, Footnotes U1, AQ
Footnote AQ was returned because “1921 Elvis Presley Blvd“ is an actual record found in the USPS
ZIP+4 database, but that record has a different +4 code (6947) than what was presented on the input
address (1000). The input address +4 code of 1000 corresponds to a ZIP+4 record that is a PO Box.
USPS CASS rules state that we are required to return the matched address, but with the input +4 code,
and the ZIP+4 database record fields from the record associated with the input +4 code. This may lead
to some confusion because the Carrier Route ID and the record-type code that are returned will
represent a PO Box address, however, this address clearly matches to a street-style address. The AQ
footnote is set to indicate this condition.