Written by Head Zip | 26 February 2011

How we started working with zip code data

Frankly, we started this business out of frustration. Our background is in strategic consulting for Fortune 500 companies. As part of that job, we regularly conducted extensive demographic analyses to determine marketing strategies, store placements, and overall growth strategies. To do this we often want to link company level data (at the address or zip code level) to broader demographic data sets available from sources like the US Census Bureau. We found that the data to link zip codes to these these disparate elements was not readily available.

Why is good zip code data so hard to get?

Zip codes are controlled by the USPS. They are fundamentally a tool for them to sort mail and get it delivered to the address in the most efficient way possible. The USPS builds zip codes from the bottom up. Almost each building or set of buildings has a specific 9 digit zip code (aka Zip+4) that identifies it specifically. Then the USPS constructs what are called "Carrier Routes," which are literally the path that the mailman will follow on his delivery schedule that link a set of Zip+4 addresses. A set of carrier routes forms what we know as a 5 digit zip code.

Given new construction, the changing postal patterns, and population trends, the postal service often needs to change the carrier routes; and therefore the boundaries of the zip code will also change. There are thousands of changes a year to the dataset.

How we create the best zip code data around

We receive most of our data under license from the United States Postal Service, and supplement it with additional analysis, synthesis, and appended data. Just like the postal service, we start from the bottom up with detailed, house level Zip+4 data. The datasets we receive from the postal service contain over 80 million rows of data! As our IT guy said, to paraphrase the immortal words of Roy Scheider as Brody in Jaws, "I think you'll need a bigger computer!"

Because of the detailed nature of the USPS zip code data, we have to conduct an exhaustive analysis of the data to get it into a format which is actually usable for everyone who is not a mailman. (In layman's terms, we "crunch" the dabase.) This produces a set of files which are actually manageable and extract the most useful data elements you would want to use from zip code data to link to your datasets or use in your applications.

And because all of this changes so frequently, we do all our analysis each month to ensure that we are delivering the best quality data in the easiest to use format straight to you.

Transforming zip code data into 3 and 5 digit zip code maps

We build our maps from the bottom up using the latest Tiger data shapefiles available from the US census, which are the core component of almost all GPS mapping services out there today. We are licensed providers of a product from the USPS which correlates Zip+4 addresses to the Tiger shapefiles (called Tiger/Zip+4), and as a result creates highly detailed latitude and longitude geocoding for Zip+4 addresses. We then combine this data to create our latitude and longitude data for each zip code in the nation as well as build robust, accurate, and clear zip code boundaries that can be overlaid onto county and state geographic lines.

Our guarantee

We take great pride in the accuracy of our zip code data and want you to be satisfied. We have a satisfaction guarantee. Please email us if you are not satisfied with your product and we will make things right!