ZIP Code Lookup

To look up a ZIP Code in your state or city, you can leverage the USPS ZIP Code Lookup tool available on the USPS website. The tool will provide you with the corresponding ZIP code once you enter the address, city, and state information. This tool is free to use and also makes sure you have accurate postal details for sending and receiving mail.

Businesses need USPS ZIP code lookup for many reasons, including creating accurate mailing lists and making decisions. They can do so by visiting the USPS website and searching for their area or locality. Also, they can use an address validation tool to get a complete list of ZIP codes for their mailing lists.

ZIP codes help understand customers’ locations, letting companies know their most customer-dense areas and how to expand sales.

But that is not all!

ZIP codes have many use cases, which makes using the ZIP code lookup a must. This blog discusses the meaning and uses of ZIP codes—with how to use the ZIP code™ lookup on the USPS website.

Key Takeaways

• A ZIP code is a 5-digit numerical code that indicates a specific destination post office or mail delivery area.
• The initial three digits of a ZIP code indicate the central mail processing facility. The fourth and fifth digits signify the specific area within the city or town.
• Only some US locations have a ZIP code. Thus, using the USPS ZIP code lookup only works sometimes.
• Only some US locations have a ZIP code. Thus, using the USPS ZIP code lookup only works sometimes.
• Alternatively, you can use PostGrid’s address verification API to add missing ZIP codes to your mailing lists.

A ZIP Code is a 5-digit numerical code that designates a specific destination post office or mail delivery area, determining the final sorting and delivery location for letters. It signifies a grouping of delivery routes utilized by mail carriers and regions serviced by the United States Postal Service (USPS).

The acronym “ZIP” in ZIP Code stands for “Zone Improvement Plan.” The 5-digit ZIP Code consists of three primary components: the national area, the region or city, and the delivery area.

USPS has divided the United States into ten ZIP Code areas, numbered 0-9, starting in the northeast. You can use the ZIP code lookup USPS to find them for specific locations.

Understanding a ZIP Code

Before diving deep into what the USPS ZIP code lookup is, please consider the following ZIP Code example: 91001. Once the first number is assigned based on the National Area, the subsequent two numbers are allocated according to a city, often starting with the main town or city in that region. The ZIP Codes then progress alphabetically.

The initial three digits of a ZIP Code collectively indicate the central mail processing facility, also known as a sec center or sectional center facility, to which the ZIP Code belongs. This facility serves as a specific zone or area's mail sorting and distribution center. 

Some sectional center facilities may have multiple three-digit codes assigned, making the ZIP code lookup complicated. For instance, Merrifield's Northern Virginia sectional center facility has the ZIP Codes starting with 220, 221, 222, and 223.

The fourth and fifth digits of the ZIP Code signify the specific area within the city or town. For instance, if a letter carries the ZIP Code 47722, the USPS can deduce that it is in Indiana (4), Vanderburgh County (77), and the vicinity of the University of Evansville (22).

Matching ZIP Codes With Different Places

Only some US locations have a ZIP code. Thus, using the USPS ZIP code lookup only works sometimes. 

There are insufficient deliverable addresses to establish a mail route, rendering a ZIP code unnecessary—primarily in remote and rural areas. If you're seeking seclusion or to live off the grid, these regions represent some of the most isolated areas in the country. For finding local businesses and services in your area, Loc8NearMe can be a valuable resource.

Assigning ZIP codes to specific counties adds another layer of complexity, with as much as 25% crossing county lines. The same complexity arises when associating ZIP codes with congressional districts, metro areas, time zones, area codes, and more, often leading to overlapping boundaries. 

Thus, businesses should be careful when using USPS ZIP code lookup by address for mailing, marketing, and other purposes.

It's crucial to understand that ZIP codes help streamline mail delivery. They might not necessarily align with established boundaries like cities, counties, or states.

If it is more practical for a mail carrier to cross state lines to deliver mail, the ZIP code “boundary” may extend beyond state lines, although this is not the norm. Some ZIP codes, such as 65733, 71749, and 73949, serve as examples of codes that cross state lines.

City assignments further complicate matters for USPS ZIP code lookup by street address, as the USPS only sometimes uses the actual city where a ZIP code is situated. The assignment of cities to ZIP codes is more general, usually reflecting the name of the main post office.

For example, many ZIP codes in St. Louis County, Missouri, are labeled as Saint Louis, even though they may more accurately correspond to the names of smaller cities within the county.

 Also Read: ZIP Code Validation

How to Find ZIP Codes on the USPS Site

You can find ZIP codes on the USPS website in two ways: by address or by city or state. Also, you can find cities by entering the relevant ZIP codes.

By Address

The first option, wherein you must find ZIP codes by address, requires you to enter a residential or commercial street address, the associated city, and state to get the ZIP code. It can be the most complex option because usually people or companies finding ZIP codes don’t have so many details. However, it is a great option for those who have all the address elements except the ZIP code and want to add this missing information. 

Also, it can help those who have a mailing list with some missing ZIP codes and need to complete the blank spaces. 

By City and State

The next option is good for those looking to get all the ZIP codes of a particular city. You can enter the city and the associated U.S. state to get the complete list of ZIP codes in one file. This is helpful for marketers who need to collect this kind of information for planning their upcoming advertising campaigns.

Cities by ZIP Code

This is an additional feature offered by the USPS, wherein you can enter a ZIP code to view the cities that it covers. It is kind of a reverse lookup, but it is helpful for those who have the ZIP codes but not the related information with them.

Who Needs to Look up ZIP Codes

People Who Need to Send Mail

Individuals who want to send mail to another locality, city, or state need to write the destination ZIP codes in their mail pieces. However, not everyone has that information. Thus, they can use the ZIP code lookup for confirmation to ensure they don’t send mail to incorrect addresses.

Businesses That Need Mailing List Verification

Companies need ZIP code information for two primary reasons: marketing and delivery. They need a validated mailing list with correct ZIP codes so that they can mail customer orders on time. Also, such verified mailing lists help them send marketing mail to relevant prospects, increasing their chances of getting higher responses.

However, please remember that the USPS ZIP code lookup tool only works in the U.S. Businesses that want to mail globally can use PostGrid’s Address Verification solution, which validates addresses of 245+ countries and territories. Also, it allows you to check up to a million addresses in one go, making the tool much better than that of the USPS.

The U.S. Postal Service employs a standardized format for all U.S. addresses, emphasizing using uppercase letters to prevent confusion. Ensure you include the apartment or suite numbers where applicable, employing valid USPS acronyms and abbreviations without periods. 

Here is an example of where to add ZIP codes to make USPS ZIP code lookup easier for your company:

Miller Inc.
8 5th AVE
New York City, NY  10110-0001

Like the example above, senders must use a single space between the city and state and a double space between the state and the ZIP code for optimal accuracy and delivery speed. Additionally, employ a nine-digit ZIP code.

While many individuals may be unaware of the four-digit code associated with their ZIP codes, prompting a potential challenge in obtaining such information from clients, leads, or customers, a USPS ZIP code lookup tool can seamlessly append these codes.

Beyond adhering to the fundamental USPS standard format, there are essential considerations for effective mail processing:

1. Place the suite or apartment number above the delivery address if space is insufficient on the same line instead of below it.
2. Utilize a USPS address verification tool to determine the ZIP+4 code.
3. When delivering mail to an address rather than a specific individual, address it to a generic title such as “Postal Customer,” “Occupant,” or “Resident” instead of a name.
4. Pay careful attention to directionals like “east” and “west,” as their omission or inaccuracy may impede accurate mail delivery.
5. Recognize that despite incorrect addressing, USPS might deliver some items after making some changes to the location. However, such errors incur additional costs and resources for the Post Office, leading to surcharges for your business.

 Also Read: How do I Validate Addresses with UPS?

ZIP Code vs Other International Postal Codes

Postal codes in the U.S. are known as ZIP codes. They help in identifying geographical areas and for the correct routing and delivery of mail. ZIP codes are mainly used in the United States, but other countries have their own postal code systems. Here is a comparison of the U.S. ZIP code with other popular international postal codes:

United States (ZIP Code)

1. Format: The ZIP code consists of five digits (e.g., 90210). There is also an extended version (ZIP+4) that adds a hyphen and four more digits (e.g., 90210-1234), providing even more precise location information.
2. Purpose: Used to identify a region, city, or area within the U.S. ZIP codes are linked to specific post offices and delivery routes.
3. Geographical Division: ZIP codes typically break down into larger regions first (e.g., by state or major city), then more specific areas (e.g., neighborhoods, streets).

United Kingdom (Postcode)

1. Format: Postcodes in the UK are alphanumeric, usually consisting of 5 to 7 characters (e.g., SW1A 1AA).
2. Purpose: UK postcodes are used to identify areas for sorting and efficient mail delivery. The codes are precise and can correspond to a specific address or building.
3. Geographical Division: The UK postcode system is divided into different levels of precision. The first part of the postcode (outward code) identifies a larger area (such as a town), while the second part (inward code) identifies a more specific location (such as a street or a building).

Canada (Postal Code)

1. Format: Canadian postal codes are also alphanumeric and follow the format “A1A 1A1” (e.g., M5A 1A1).
2. Purpose: Canadian postal codes are used for sorting mail within a specific area. The system helps ensure that mail is delivered efficiently.
3. Geographical Division: The first character in the postal code represents a province or territory, while the subsequent characters break down the region into more specific areas, often down to a specific street or block.

Australia (Postcode)

1. Format: Australian postcodes are numeric and consist of four digits (e.g., 2000).
2. Purpose: Australian postcodes help in the sorting and efficient delivery of mail across the country.
3. Geographical Division: The postcodes are organized regionally and are assigned based on the area's delivery network, with codes increasing numerically as they move from the south to the north of the country.

You can search ZIP codes on the USPS website by entering the street address, city, or state.

However, the USPS ZIP code lookup by address or other elements does not confirm whether a person or organization is at the location.

Also, try searching for company locations with and without the organization’s names if you don’t get proper results with one search. You can also use different versions of these names until you find the correct ZIP code.

Input whatever address details you have, whether comprehensive or minimal. With a complete address, you can ascertain the deliverability of mail to that specific location.

If you only input a street name with the city and state or ZIP code, you get a compilation of all house numbers on that street. 

Alternatively, entering a house number and ZIP code yields a roster of all addresses sharing that house number within that ZIP code.

However, this tactic might be daunting and time-consuming to conduct a ZIP code lookup or search.

Hence, you can use PostGrid’s address verification API to add missing ZIP codes to your mailing lists.

PostGrid can

• Add missing address data.
• Check whether your existing ZIP codes are correct.
• Add ZIP+4 codes to make your addresses more deliverable.
• Provide geocoding, DPV, and other additional information.
• Standardize, parse, and validate all postal addresses within the US and outside.
• Help you get the benefits of USPS ZIP code API lookup without doing anything in-house.

Request a demo now to understand how the ZIP code lookup works and how we help!

 Also Read: What are State County FIPS Codes?