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How to Find an Address by Postal Code

Postal Codes (or zip codes) are assigned to geographic areas in order to make the sorting of mail easier. The system went into effect in 1963 with a five-digit code, and in 1983 four digits were added to existing five to make the code more specific. A postal code refers to a set geographic zone, not a city or county. Large cities, such as New York or Los Angeles, can have several postal codes within city limits, and new codes may be added as the city grows.

Nine-digit postal code (zip code)

Instructions

- 1
  Determine the nine-digit that corresponds to the address you are looking for. A five-digit code will provide a large area, usually a whole city.
- 2
  Separate the code into its constituent parts. For a nine digit code (12345-6789) the first three digits refer to a large area, such as a city, the second to a Post Office facility, the next two to a sector or set of blocks, and the last to a segment of those blocks or a part of a street.
- 3
  Consult the Address Information System Viewer (AIS) to determine the location of your address. AIS can be obtained through the USPS National Customer Support Center (1-800-238-3150) on a DVD. Printed copies of the AIS are no longer available through the USPS.
- 4
  Enter postal code into an online postal code lookup tool. (See Resources)