Have you ever seen an excessively large amount of US traffic supposedly coming from Coffeyville, Kansas in Google Analytics? This specific geolocation may even contribute the most amount of sessions worldwide. 

What is the Coffeyville Effect?

Even though you may not be targeting Kansas, internet users who enable IP masking tools will report their location back as the exact geographical center of the U.S. which is Coffeyville, KS. 

This effect can also happen with some mobile devices that report back incorrectly or as “unknown”. 

Analytics and Ad Serving programs will often attribute those unknowns to Coffeyville. An example of this that you might have experienced is when your phone’s location service (such as on Google or a weather app) estimates you are in a city several hours away when you are connected to mobile data instead of home wifi.


Is Google the Problem?

Google Analytics provides a number of geographical dimensions, such as City, Country, Continent, etc. The values for these dimensions are automatically derived from the IP address of the hit. The Coffeyville Effect is what happens when a location is not accurately determined.

Google sends the IP addresses of traffic sources to a third-party data source to determine the location. If the third-party source determines the record of the visitor location is accurate, Google Analytics populates the fields with the location data. If the third-party source determines the location cannot be found, the value of the corresponding fields will register as “(not set)” and then be assigned the default location of the center of the US.

If Coffeyville, Kansas is an inaccurate location for your traffic sources, it’s likely that this is the fault of one of the third-party data sources that Google uses, rather than Google itself. Unfortunately, these data sources are not disclosed by Google.