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Counties by ZIP Code Database

Updated Quarterly
Download Anytime
Annual Subscription

Database Specs & Features

  • Immediate Download

    Download is available immediately upon purchase and for the duration of the annual subscription.

  • Quarterly Updates

    A monthly update of this database is not necessary, so we update our database quarterly and recommend that you download quarterly as well.

  • Free FTP (upon request)

    To update your database without human intervention, we can provide you will your own FTP site that you can write a script to access. Just request it after purchase.

  • Data Format - CSV

    Comma-Separated Values (CSV) Text File

  • 5 Digit ZIP Code

    Official U.S. Postal Service five digit ZIP Code

  • County

    The name of the county in which the ZIP Code is found. This is a one-to-many (ZIP Code to County) relationship.

  • County FIPS

    Federal Information Processing Standard (FIPS) 3‐digit county. FIPS codes are not available for all areas (APO, FPO, some U.S. Territories).

  • Percentage

    This is the percentage of the zip code area which this county occupies. If there is only one county for the zip code it will be '100'. This is a rounded number, so there could be cases where not all totals equal 100%.

  • Sequence Number

    This is for prioritizing the counties within a ZIP Code (sequence 1 is the main county for the ZIP Code).

  • State

    Official U.S. Postal Service state abbreviation

  • State FIPS

    Federal Information Processing Standard (FIPS) 2‐digit state. FIPS codes are not available for all areas (APO, FPO, some U.S. Territories).

  • City

    Official city name used by the U.S. Postal Service

ZIP Codes cross county lines about 20% of the time. Many ZIP Codes span several counties and some even cross state lines. This Counties by ZIP Code product was created to identify ZIP Codes that span multiple counties (ZIP Code to County database), isolate one-to-one County to ZIP Code relationships, and/or identify all ZIP Codes within a given county’s boundary.

This is a one-to-many (ZIP Code to County) database. The file includes: all counties by ZIP Code, an estimate of the county percentage covered by each ZIP Code, a sequence showing the predominate counties for each ZIP Code, and much more (see features at right). more...

More accurate than similar products! Here’s why: Counties by ZIP Code graphic
zip code to county

We accept PO's - call for details...
commercial grade
free ftp upon request

Free FTP - Beyond our immediate download functionality, a customer may wish to access their database over FTP. This is now freely available to any customer upon request. We will provide an FTP location populated with up-to-date copies of your actively subscribed database product.

Multiple Counties by ZIP Code

This product is ideal for applications where its critical to have a ZIP Code to County database showing all counties by ZIP Code. For example:

  • Tax calculations
  • Insurance rate calculations
  • HMO coverage area determination
  • Sales territory assignments
  • Fraud detection
  • Data Verification
Learn more: view the Product Documentation
Watch our Multiple Counties by ZIP Code video: Counties by ZIP Code
Watch our Accuracy Matters video: ZIP Code Latitude Longitude Accuracy Matters

Database Sources

We are licensees of USPS database products, but we enhance our ZIP Code to County database based on decades of experience to provide you with the most accurate product available.

Affordability and Simplicity

  • Low Cost
  • One Year Access
  • Updated Quarterly
  • Unlimited Downloads
  • Unlimited User Licensing Available
  • Money Back Guarantee


Cannot be resold, transferred, or used to compete with (as outlined in license agreement). One copy per application or business entity.

Click for data sample and field names in Comma Separated Values file format (*.csv) database.