ZIP+4 Codes (aka 9-digit ZIP Codes) are 5-digit ZIP Codes plus 4 digits identifying smaller geographic segments within each ZIP Code. Within a standard 5-digit ZIP Code, there are 5,000 addresses on average, whereas a ZIP+4 may be less than a half-dozen. When combined with a latitude and longitude coordinate, this offers a significantly more precise geolocation. Our best latitude and longitude coordinates cover 99.9% of the records in this dataset (a record without an exact match will have the latitude and longitude of the ZIP Code).
The last 4 digits typically represent routes within delivery areas. This could be a row of houses on one side of the street or a city block. However, there can be multiple ZIP+4 codes assigned to the same address. This may happen for a high-rise building, large business, or a multi-tenant apartment complex. Furthermore, a ZIP+4 Code often represents individual PO Boxes found in a single Post Office. Thus, numerous ZIP+4 Codes would be in the same place.
A difficulty with a ZIP+4 database is its massive size, especially given how frequently the data changes. There are over 48 million ZIP+4 records with files well over 100 MB. To help, we consolidate ZIP+4 Code ranges that share the exact latitude and longitude (see example below). Doing so shaves off 13 million records: around 30%. We’ve also done our best to minimize the size of this file by reducing large amounts of repetitive data. If you need fields that have not been included, you may combine this with any one of our other ZIP Code products.
As mentioned in the summary, we reduce the overall file size by combining ZIP+4 ranges within the same latitude and longitude. For example, an address with the ZIP+4 of 12345-0800 would match to the first record shown (right) because 0800 is within the range of 0001-0999.
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Comma-Separated Values (CSV) Text File
This is the Official U.S. Postal Service five digit ZIP Code.
A 4-digit Beginning +4 Number. This is the starting range for the ZIP+4 code.
A 4-digit Ending +4 Number. This is the ending range for the ZIP+4 code.
The Latitude is a number followed by up to 6 decimal positions.
The Longitude is a number followed by up to 6 decimal positions. A negative sign indicates the Western hemisphere.
