Carrier Routes vs. ZIP Codes: Which Should You Use?

ZIP Codes are the default way most people think about a mailing area. Carrier routes are often the better one. Here is the difference and when it matters.

ZIP Codes were built for sorting mail

A ZIP Code is a mail-processing area. It can contain very different neighborhoods: apartments and estates, commercial strips and quiet cul-de-sacs. Mailing an entire ZIP Code means mailing all of them.

What a carrier route is

Each ZIP Code is divided into carrier routes, the set of addresses a single letter carrier delivers to. Routes are much smaller than ZIP Codes, so selecting routes lets you choose neighborhoods rather than whole ZIP Codes. Route-level characteristics such as median income or home value help decide which routes fit your offer.

Postage: carrier-route prices

USPS Marketing Mail offers carrier-route prices for mail prepared in walk sequence for each route. According to the USPS Domestic Mail Manual (section 243, accessed September 2026):

• High density prices require at least 125 pieces for each carrier route (letters).
• High density plus prices require at least 300 pieces for each carrier route (letters).
• Saturation prices require mailing to at least 90% of the active residential addresses, or 75% of the total active possible delivery addresses, on each carrier route receiving the mail.

Requirements change and include preparation details beyond these thresholds, so confirm current standards with your mail house before each campaign.

When ZIP Codes are fine

• Broad regional campaigns where neighborhood differences don't matter
• Named consumer or business lists where selections already do the targeting
• Quick tests where precision is less important than speed

When carrier routes are better

• Saturation or near-saturation residential mailings
• Offers that fit some neighborhoods in a ZIP Code but not others
• Trade areas that cut across several ZIP Codes

EDDM or an addressed saturation list?

Every Door Direct Mail (EDDM) is a USPS product that delivers unaddressed pieces to every address on selected routes. An addressed occupant list gives you route selection informed by data, addressed pieces and the ability to combine routes with named records. Which is right depends on the campaign.

Learn more about carrier-route targeting.

General information only. Postal standards and legal requirements change; confirm current rules before each campaign. Questions? Talk to a data expert.