Usps Zip Code Lookup
Mireille Duhon
A ZIP+4 Code is a 4-digit code appended to a standard 5-digit ZIP that helps the USPS sort, route, and deliver mail more efficiently. The last 4 digits of these 9-digit ZIP Codes usually represent 6-20 delivery points on a USPS carrier route.
Also called plus-four codes, 9-digit ZIP Codes, and full ZIP Codes, you can look up USPS ZIP+4 Codes using various tools. Smarty provides some easy-to-use options for single ZIP+4 Code lookups by address, ZIP+4 Codes in bulk (up to millions at a time), and ZIP plus 4 lookup via API. You can try them out here, or read on to learn more about ZIP+4 Codes.
ZIP+4 Codes are 4-digit codes appended to the original 5-digit USPS ZIP Codes. Using the full ZIP Code with the extra 4 digits when mailing via the USPS ensures the fastest, most accurate mailing possible.
ZIP plus 4 lookup tools don't just do a full ZIP Code lookup. Before you get the +4 Code, your address is taken through the full address standardization and validation process confirm the address is mailable.
These codes indicate a specific delivery route, meaning the actual path the mail truck would travel in a single drop-off. Usually, this comprises 5 to 20 homes or locations. The USPS also assigns ZIP+4 Codes to PO Boxes. Typically, each PO Box gets its own +4 Code, which often matches the box number.
The extra 4 digits on ZIP Codes identify segments of fluid postal delivery routes. They're not permanent lines, so a 9 digits ZIP Code can change regularly. Five-digit ZIP Codes also change, but they do so infrequently; it's less likely that you will live in a ZIP Code when it changes. Not so for the last 4 digits of Zip Code numbers.
The +4 on a ZIP Code can change as frequently as every 30 days. In fact, 5% of all addresses get their ZIP+4 Code changed each month. Quantity of postal employees, new construction, remapping delivery areas, etc., are just a few things that cause ZIP+4 Code changes.
Those benefits are just the beginning. If you're getting the ZIP+4 Code, you're already validating and standardizing the address and address validation improve business results across all types of organizations. Read our ebook to learn how:
The Zone Improvement Plan (ZIP) was something the USPS came up with to make it easier to ship letters and packages across the country. ZIP helps divide the country into different "zones" according to the distribution of mail, which accelerates sorting and delivery.
On July 1, 1963, the Post Office Department launched the Zone Improvement Plan. At the same time, they introduced the world to Mr. ZIP or "Zippy." Zippy is the official ZIP Code mascot pictured on our ZIP Codes 101 page. They also released the ZIP Code jingle:
As the US population has increased and scattered since 1963, it's been necessary to expand the system to make room for everybody and their dog. That's where the "plus 4" part comes in. We're getting ahead of ourselves, so let's start with the basics.
If you're mailing a letter from Boston to Seattle, the mail carrier in Massachusetts doesn't care what the street address of the destination is. It's what you might call "outside his jurisdiction." He just needs to know which mail carrier to send it to so the appropriate mail carrier can get it to the address.
A postal worker can only cover so much ground on a given day. And since the USPS has a standard of delivering in the rain, sleet, or snow, that rules out the possibility of doing the service of delivery in stages (some today, some tomorrow). That means any given post office only serves what it can reach in a day. ZIP Codes reflect that.
Typically, a ZIP Code ties to a post office; by that, we mean every one of the latter has one of the former. You might think of ZIP Codes as a mailing address for a particular post office. Some handle more than one ZIP Code, but a one-on-one game plan is a standard.
It's essential to note that ZIP Codes aren't "boundaries." They're a collection of delivery routes. They don't follow geographic or administrative boundary lines; they can cross city, county, and state lines. They follow where the delivery trucks go.
Some ZIP Codes are a bit different in function. Among them are "military" ZIP Codes, which include everything from military bases (domestic or otherwise) to battleships at sea. Then there are "unique" ZIP Codes. Businesses and organizations sometimes get a dedicated ZIP Code that they don't have to share with anyone due to the volume of mail they send and receive.
These frequently benefit from bulk mailing discounts since the organization usually has a mail department that (1) presorts mail before giving it to the USPS and (2) distributes mail internally, so the USPS doesn't have to. Like standard ZIP Codes, "military" and "unique" ZIP Codes circumscribe their delivery area. For a more in-depth guide, visit our ZIP Codes page.
For many users, the best way to access the USPS ZIP+4 database is through a CASS Certified USPS address validation vendor. Like Smarty. Since the last four digits of ZIP Codes update frequently, even month-old data isn't reliable. Checking addresses regularly against the database will ensure your data remains clean.
The ZIP+4 Code database can be accessed free directly through the USPS site or the USPS address validation API. In our USPS APIs article, you will find a comprehensive list of uses and limitations of the USPS web-based tool and API. If you need a ZIP+4 Code Database, address validation might scratch your itch better than anything provided by the USPS. You can check out our ebook. It shows how to improve business results in your organization using address validation. Read it here:
If you need an answer to, "What is my ZIP Code with the extra 4 digits?" Just click one of the buttons at the top of the page, enter your address, and get your +4 Code instantly. Just remember, it's called a ZIP+4 Code, or simply a ZIP+4.
If you want to try it on a single address, you can now use our Single Address Verification Tool. Our blindingly fast US Address Verification API provides the appropriate ZIP+4 Code for every address we process.
Or you could call us instead if you'd rather talk to an actual person. (We'd offer a fake person, but we don't have one of those on staff.) Either way, we can help you ZIP your address and ZIP it well.
The Addresses API validates and corrects address information, eliminating errors, improving package delivery service and package pricing. This suite of APIs provides different utilities for addressing components. The ZIP Code lookup finds valid ZIP Codes for a City and State. The City/State lookup provides the valid cities and states for a provided ZIP Code. The Address Standardization API validates and standardizes USPS domestic addresses, city and state names, and ZIP Codes in accordance with USPS addressing standards. The USPS address standard includes the ZIP+4, signifying a USPS delivery point, given a street address, a city and a state.
The API supports customers scheduling a carrier to pick up your packages on the next USPS delivery day (Monday through Saturday, excluding holidays) for free. Carrier Pickup is available for sending packages using Priority Mail Express, Priority Mail, First Class Package Service Commercial, international delivery services, or for returned merchandise. You are able check availability, schedule, change, cancel and inquire on a carrier pickup.
The Intelligent Mail Container barcode (IMcb) provides visibility at the mail aggregate level. It is used on mailer-generated pallet labels to uniquely identify pallets and similar containers (i.e. All Purpose Containers, hampers, pallet boxes, etc.) in addition to identifying the mail owner and, it provides a link between the electronic mailing record and the physical mail aggregate.
The Domestic Labels API supports creation of domestic shipping labels with Intelligent Mail Package Barcodes (IMpb). Along with label and barcode creation in PDF, TIFF, SVG, JPG, ZPL203DPI, or ZPL300DPI format, this API validates addresses, confirms product availability, calculates postage, and generates the required Shipping Services File in accordance with USPS Publication 199.
This API provides Domestic USPS product pricing based on the characteristics of what is being shipped for Parcel Select, Parcel Select Lightweight, Priority Mail, Priority Mail Express, USPS Ground Advantage, Library Mail, Media Mail, and Bound Printed Matter. Given inputs, such as origin and destination ZIP Codes, package weight and dimensions, processing category, destination rate indicator, price type, and desired Mail Class and Extra Services, this API will return the price of postage.
The International Labels API supports creation of international shipping labels. Along with label and barcode creation in TIFF and PDF format, this API confirms product availability, calculates postage, and generates the required Shipping Services File in accordance with USPS Publication 199.
The International Prices API provides International USPS product pricing based on the characteristics of what is being shipped for Global Express Guaranteed, Priority Mail Express International, Priority Mail International, and First-Class Package International. Given inputs, such as origin and destination ZIP Codes, package weight and dimensions, processing category, destination rate indicator, price type, and desired Mail Class and Extra Services, this API will return the price of postage and Extra Services.
This API supports returning destination entry facilities (i.e., drop off locations) for a given ZIP Code to enable Parcel Select Destination Entry, USPS Connect, and Parcel Select Lightweight. This API also provides additional information about working hours, delivery type, mail class, shape, palletization, and facility type.
Once you sign-in to the API developer portal, you may get the OAuth credentials you will need to register your application 'Add App'. See "Getting Started" for further information about: signing-in, registering your application, and additional USPS account credentials you will need to integrate your application with USPS APIs.
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