United States

The United States Postal Service (USPS) introduced the original 5-digit ZIP Code system in 1963 and the expanded ZIP+4 system in 1983.

A ZIP+4 consists of the standard five-digit ZIP Code followed by a hyphen and four additional digits:

12345-6789

The additional four digits allow USPS to identify much smaller delivery areas within a 5-digit ZIP Code.

The structure can be viewed as:

12345-6789

• 12345 — 5-digit ZIP Code
• 67 — ZIP+4 Sector
• 89 — ZIP+4 Segment

Together, the sector and segment provide a much more detailed postal delivery identifier.

How Detailed Is ZIP+4?

A 5-digit ZIP Code can encompass a large geographic area containing thousands of addresses.

A ZIP+4 can identify a much smaller delivery area, including:

• One side of a street between intersections
• Both sides of a street between intersections
• A specific range of addresses
• An individual building
• A floor or group of floors within a building
• A business or organization receiving significant mail volumes
• A group of Post Office boxes
• A range of boxes on a rural delivery route
• Other specific USPS delivery segments

As a result, ZIP+4 provides a level of postal geography that is significantly more detailed than conventional ZIP Code mapping.

From ZIP+4 Codes to Geographic Polygons

USPS ZIP+4 Codes are postal delivery identifiers and are not published as official polygon boundaries.

World Postal Maps creates geographic polygon representations of ZIP+4 delivery areas by combining postal addressing information with detailed address and geographic source data.

The resulting polygons make it possible to use ZIP+4 information directly within GIS and spatial applications.

Instead of simply knowing that an address belongs to a ZIP+4, users can visualize and analyze the geographic territory associated with that ZIP+4.

ZIP+4 vs. 5-Digit ZIP Code Polygons

5-Digit ZIP Code Polygons

Traditional ZIP Code boundaries are useful for:

• Regional mapping
• Demographic aggregation
• Territory analysis
• Marketing
• General location intelligence

However, an individual ZIP Code can cover a relatively large geographic area.

ZIP+4 Polygons

ZIP+4 polygons provide substantially greater geographic precision and can support applications requiring analysis closer to the street, building or delivery-area level.

This makes ZIP+4 particularly useful where traditional ZIP Code geography is too coarse.

Applications for ZIP+4 Polygon Data

Detailed ZIP+4 geography can support a wide range of commercial and analytical applications, including:

• Address validation and geocoding
• Reverse geocoding
• Point-in-polygon ZIP+4 lookup
• Last-mile delivery and logistics
• Service territory modelling
• Telecommunications network planning
• Insurance territory and risk analysis
• Property and real-estate analytics
• Customer and market segmentation
• Direct marketing
• Site selection
• Utility analysis
• Emergency and public-sector applications
• Location intelligence platforms

ZIP+4 polygons can also provide an intermediate geographic layer between individual address points and larger ZIP Code territories.

Nationwide 5-Digit ZIP Code Boundaries

World Postal Maps also provides conventional 5-digit United States ZIP Code polygon boundaries.

These datasets provide nationwide ZIP Code geography for organizations that do not require the additional detail available with ZIP+4.

Both 5-digit ZIP and ZIP+4 products can be supplied depending on the geographic resolution required by your application.

United States ZIP+4 Data Updates

USPS maintains and updates ZIP+4 information on an ongoing basis as addresses, delivery routes and postal assignments change.

World Postal Maps can provide updated United States postal polygon data on a:

• Monthly
• Quarterly
• Annual

schedule.

Update frequency can be tailored to the requirements of the application and licensing agreement.

Data Formats and Licensing

United States ZIP+4 and 5-digit ZIP polygon datasets are available in standard GIS and spatial-data formats suitable for use with:

• PostgreSQL / PostGIS
• Esri ArcGIS
• QGIS
• Cloud GIS platforms
• Spatial databases
• Web mapping applications
• Enterprise location-intelligence systems

Commercial licensing is available for:

• Internal business use
• Enterprise applications
• SaaS and web applications
• Derived products
• Location-intelligence platforms
• Data enrichment
• Other commercial applications

Request a ZIP+4 Sample

Because ZIP+4 geography is significantly more detailed than standard ZIP Code mapping, we recommend evaluating the data using a representative sample area.

Contact us at info@worldpostalmaps.com to request:

• A ZIP+4 polygon sample
• Coverage statistics
• Technical specifications
• Available formats
• Update options
• Commercial licensing information
• Pricing

Check out our Coverage page for data availability.