Cool Zip Code Tools
I was recently asked to quote on a project that involved determining a person’s:
- ZIP+4 code from a street address and five-digit ZIP code and
- the Congressional district from the ZIP+4 code.
My first thought was to contact the U.S. Postal Service to see what they offered. They offer something called the ZIP+4 Product, which is a big text file, that you’d have to import into a database to use properly. It costs $900 for a one-year subscription.
The client thought this was kind of expensive, so they suggested that we make the user responsible for inputting the appropriate ZIP+4 by adding a link that would pop up another window with the appropriate USPS.Com page. This is definitely a low-cost solution, but it might turn away people who would otherwise complete the form. It’s also more prone to human error.
Both of these approaches require yet another database to determine the person’s Congressional district.
Another solution is the ZIP+4 database from Zipcode Download. For $250, they’ll sell you the current data. For $400, they’ll sell you a one-year subscription, including quarterly updates. The cool thing about this database—at least as far as this project is concerned—is that it also includes the Congressional district number. A very similar product is ZipInfo.Com, although for a slightly higher price ($500 for a yearly subscription with quarterly updates).
Both ZipCodeDownload and ZipInfo also sell zip code databases with latitude and longitude information. With this information, you can calculate distances between zip codes or find zip codes within a certain radius of a zip code. These are very useful functions for many Web applications.