Geolocation in Google Analytics can be useful in determining where to spend your marketing dollars. Of course, you don't know why the users are in a given market, but seeing that people from Chicago have different behavioral patterns from southern Californians can be useful.

Looking at location data for a Michigan city, we noticed a spike in location data from Nashville which was more than could be explained as normal traffic. We wanted to know what this traffic was. Was it real traffic caused by some local earned media or perhaps bot traffic?

First Clue: Nashville Traffic is 94 Percent Mobile!

Looking at the city of Nashville traffic to a Michigan city, it turns out that a whopping 94 percent of this traffic is from mobile devices, yet only 61 percent of the overall site traffic is mobile. This discrepancy is a strong indicator of anomalous data. Something is going on with the Nashville traffic.

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For the same Michigan destination, this example of Chicago traffic is what city user and engagement data (broken down by device category) normally looks like. Note that mobile traffic from Chicago is 59.29 percent, which is nearing that 61 percent figure —the site’s overall site traffic from mobile.

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Mystery Solved

It turns out that when you are using cell service, your network provider can map your IP anywhere they want. It is common for them to map through centralized data centers. When that happens, location data is reported based on wherever the cell provider routed your IP. Some providers, in some areas, may correctly map to the physical location of the mobile device; still others may report entirely different states. In tests, we have seen phones report location as far as 500 miles away from their actual location. We have also seen traffic spiking in Orlando, Bentonville, Los Angeles, and other cities.

If you’re curious, you can see where your cell service is mapping your location by turning off Wi-Fi and searching, "What's my IP location?" Right now, my phone says I'm in a city 100 miles away.

The main lesson here is that location data for mobile in Google Analytics is unreliable. Don't increase your mobile ad spend in Nashville or some other city because it seems like it’s suddenly a hot market; Google Analytics can only report what it's told. In this case, it's reporting inaccurate location data from the cell providers.