ZIPs and FIPS: Codes You May Need – And Why

We tend to think of ZIP codes as geographic markers. They are–sort of. Having only the ZIP code for a building can give you a general idea of where it is located in the United States. We know that lower-numbered ZIP codes are associated with locations in the eastern part of the country, with numbers generally getting larger to the west. 

But we also know that ZIP codes cover a large area and can cross state boundaries. They aren’t reliable geographic position indicators. The reason is the US Postal Service developed ZIP codes to align with postal delivery routes. Using ZIP codes for any reason other than postal delivery can be misleading. The results may not be what you expect. 

County-Level Precision

What if you needed to know the county in which a person resides? If the only information you had was the person’s ZIP code, you’d be in trouble. ZIP codes have nothing to do with the lines that define a county. One ZIP code could include addresses in multiple counties and a single county might include hundreds of ZIPs!  

If the county is an important data point for you, there’s another way to go. The Federal Information Processing Series (FIPS) is a set of 5-digit codes that designate every county (or similar jurisdiction) in every US state. The government developed FIPS codes to assure smooth data exchanges across technical communities, contractors, and government agencies and for data security purposes. 

Many national government agencies, including the US Census Bureau, US Health and Human Services, and the National Weather Service, use FIPS codes. Local government also uses the codes for applications such as sales and use tax calculations and public health. 

Reduce Errors

FIPS codes are better values to store in databases than county names. People can misspell county names, causing inconsistent or incorrect matching. Consider Sainte Genevieve County, Missouri. One can easily see this county name recorded as Saint Genevieve, Ste. Genevieve, or St. Genevieve. Common county names could cause problems as well. Thirty-one states have a county named “Washington” for example. Matching on a consistent five-digit number is more reliable. 

Another good quality of FIPS codes is they rarely change. ZIP+4 codes, by comparison, do change frequently as the US Postal Service modifies their delivery networks, new homes are built, or post offices are relocated.

Organizations that must make business decisions based on the county in which an address is located need to add the FIPS codes to their databases. FIPS codes determined from postal addresses are consistently accurate. If your company needs to add FIPS as a data element, you’ve got to first ensure your postal addresses are accurate and standardized. That’s the job of Firstlogic’s Address IQ^® software. Address IQ, formerly known as Firstlogic ACE^®, cleanses your address data by checking against the authoritative USPS^® CASS™ database. The software adds ZIP+4 codes and references resources such as DPV^®, LACS^Link®, USPS^® NCOALink^®, and Suite^Link® to ensure the addresses in your database are current and correct. Address IQ is also capable of appending the five-digit FIPS codes discussed in this article. 

Uses for FIPS Codes

Once your data includes FIPS codes, you can accurately determine the county in which an address is located. Many applications rely on this information to assess taxes, administer elections, distribute benefits such as food stamps, disseminate public information, select residents for jury duty, and more. 

Commercial applications can also take advantage of the unique geolocation data that FIPS codes offer. Many times, a precise location determined by latitude and longitude is unnecessary for simple tasks, such as segmenting a mailing list. Knowing the county of residence is enough information to ensure you don’t distribute communications pertinent to one county to residents of a neighboring county. 

Any organization that accesses county-level government information, such as weather data, can connect to those government sources easily via FIPS codes. Property insurance premiums, for instance, often depend on the chance for weather-caused damage such as hail, high winds, or flooding. Weather patterns can vary by county, so referencing location-based weather information from the National Weather Service helps insurers compute the cost and deductible figures for property insurance policies. 

What’s in the Codes?

The first two digits of a FIPS code designate the state in which each county is located. The government assigned the codes sequentially, starting with 01 for Alabama, 02 for Alaska, etc. Remaining codes were assigned to the states alphabetically, with a few gaps left to allow for any possible new states to be added to the union, such as American Samoa or Guam. 

The last three digits of FIPS codes correspond to a county. These digits are also assigned via an alphabetical list of counties within a state. The first alphabetical county in a state receives code 001, the second will be assigned 003, etc. Only odd numbers are used, leaving room for expansion should new counties be added at a later date. 

ZIP codes are great for postal delivery. They can even be useful when a precise physical location is unnecessary, such as locating all the furniture stores within a ZIP code. But to identify counties across the US, add FIPS codes to your corporate name and address databases. Firstlogic’s Address IQ software ensures your postal addresses are current and correct and then adds the FIPS codes for you. With FIPS codes on file, your organization can easily connect with government information sources that provide a wealth of information necessary for decision-making and analysis. 

See below for a list of state-level FIPS codes in use by organizations nationwide.