Append carrier route

How to append carrier route information

A postal carrier route is a group of addresses that receive the same USPS code to aid in efficient mail delivery. Postal carrier route codes are 9 digits: 5 digits for the ZIP Code, 1 letter for the carrier route type, and 3 digits for the carrier route (e.g., "92019C005" or "84604R009"). 

A carrier route is generally associated with where a particular mail carrier delivers.

How many carrier routes and ZIP Codes are there?

There are approximately 600,000 unique carrier routes in the United States. Approximately half of these are assigned to post-office boxes, leaving approximately 300,000 that represent "boundaries," or delivery areas. These numbers change from month to month. There are about 40,000 valid ZIP Codes in the US, meaning there's an average of 15 carrier routes per ZIP Code.

Mailing by carrier route

A saturation mailing is any mailing campaign that mails to at least 90% of the residential addresses within a postal carrier route. Many mailers mistakenly believe that a saturation mailing must be conducted by ZIP Code, but USPS definitions of the maximum saturation discount use the carrier route as the defining region.

Can I get a carrier route code appended to my address file?

All major direct mail campaigns run their address files through an address standardization process known as CASS. Even non-saturation mailings should be CASS-Certified™ prior to mailing to ensure maximum delivery. 

CASS checks the addresses against a USPS file of deliverable addresses, corrects any typos in your address file, and appends the ZIP+4 and carrier route codes (along with some other codes not relevant to this documentation). You should always run the list against our CASS process before doing your mailing. With Smarty, you can use our web-based CASS software to quickly, efficiently, and cost-effectively prepare your mailing list with carrier routes.

You can quickly and easily group addresses together with the carrier route information. This allows you to better target specific areas within a ZIP Code. Because carrier route data is constantly updated, it's important that your address lists have the latest, most accurate information.