Address Lookup API / USPS ZIP+4

USPS ZIP+4 data for the USA

The United States Postal Service maintains a database of US addresses with ZIP+4 codes which can be used for address lookup and validation.

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Key features of the USPS ZIP+4 dataset

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ZIP+4 codes

5-digit ZIP codes were introduced in the USA by the United States Postal States (USPS) in 1963. ZIP is short for Zone Improvement Plan. In 1983, the USPS rolled out ZIP+4 codes with four extra digits to designate more specific locations.

About the USPS ZIP+4 code

The structure of a ZIP+4 code

An ZIP+4 is a 9-digit code split into two parts:

20500 - 0001

The national area representing a group of US states

The region or large city within the national area

The area of the city, town or village

The sector or several blocks

The segment or one side of a street

The structure of a ZIP+4 code

US address format

PRESIDENTRecipient name
1600 PENNSYLVANIAStreet address
WASHINGTON DC  20500-0001Town State  ZIP+4 code

Key details

  • Uppercase is recommended
  • State should use the official 2-letter state code
  • ZIP+4 code should follow the state code with one or two spaces

Use Postcoder to access USPS ZIP+4 data with our simple and secure API

Postcoder is hosted on a leading cloud platform in the UK and Ireland, and is supported by our friendly team of addressing specialists.

  • Secure HTTPS connection
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