US Postal mail containing carrier route codes can be pre-sorted to the carrier route level to take advantage of pre-sort postage discounts.
A carrier route is the address group that the USPS uses to aid in the delivery of mail. This is a combination of 9 digits. The first 5 digits are the zip code,
then one letter for the type of carrier route, and then the last 3 digits are the carrier route code.
CDYNE's PAV API includes carrier route data as part of its Postal Address Verification solution.
Click here for a full list of all PAV return values.