Although we believe most businesses will yield a greater return on investment by choosing a superior product, we understand not every purpose requires the highest level of quality. The following is to arm you with some basic information when making a comparison. As you will see, one ZIP Code database is dramatically different from another according to its purpose, source, and verification process. Regretfully, we are seeing the term “commercial grade” applied so frequently that it’s no longer useful for determining quality or standards.
Navigating the low-end Market
You can buy repackaged USPS ZIP Code data from several sources for under $50 and often can get a ZIP-Code-like database derived from the census bureau for free. When choosing, it’s good to have some familiarity.
Some tips for things you will likely encounter when comparing:
Don't be fooled statements failing to give a source (“#1 rated”, “#1 trusted source”, “award winning”, “world's leading”).
Don't trust review sites claiming to be independent and unbiased. We know of no legitimate independent reviewers of ZIP Code data to-date.
Determine when the data was last updated, the update schedule, and refund policies.
If possible, download sample data and spot check it.
Critical Considerations
Some free or low-end ZIP Code data is derived from Census data.
Be aware that Census data does not have every ZIP Code (only for General Delivery). This misses a large percentage of the ZIPs.
Census data is only accurate to the decade.
The census bureau uses a ZCTA code (which is ZIP Code like, but not exact as illustrated below) – see census.gov/ZCTA
Others use straight USPS data. Free or low-end data offerings usually can’t bear the overhead of extensive data cleansing (and USPS data is not clean). If that is acceptable in your case, lets focus on other things to watch for:
Be particularly wary of using old data. ZIP Codes change every month.
If a ZIP Code covers more than one city, determine if you need every city (~60,000) or only the U.S. Post Office’s preferred city (~42,000). Most store-locators need the former, whereas address validating often calls for the latter. Some products have one record for each preferred city and an extra field containing all acceptable cities within that ZIP Code. ( like ours )
Unless otherwise stated, expect latitude and longitude centroids to be geometric calculations (shape-based). Shape-based often fall in the middle of forestry land, large lakes, parks (e.g. Central Park) where no people live for many miles. Coordinates centered on population density (population-based) are unique. See our ZIP Code Database for both.
