To demonstrate how powerful these other markers can be, the AP created a visual map of the movements of Princeton postdoctoral researcher Gunes Acar, who carried an Android phone with Location history off, and shared a record of his Google account.
The map includes Acar’s train commute on two trips to New York and visits to The High Line park, Chelsea Market, Hell’s Kitchen, Central Park and Harlem. To protect his privacy, The AP didn’t plot the most telling and frequent marker — his home address.
Huge tech companies are under increasing scrutiny over their data practices, following a series of privacy scandals at Facebook and new data-privacy rules recently adopted by the European Union. Last year, the business news site Quartz found that Google was tracking Android users by collecting the addresses of nearby cellphone towers even if all location services were off. Google changed the practice and insisted it never recorded the data anyway.
Critics say Google’s insistence on tracking its users’ locations stems from its drive to boost advertising revenue.
“They build advertising information out of data,” said Peter Lenz, the senior geospatial analyst at Dstillery, a rival advertising technology company. “More data for them presumably means more profit.”
The AP learned of the issue from K. Shankari, a graduate researcher at UC Berkeley who studies the commuting patterns of volunteers in order to help urban planners. She noticed that her Android phone prompted her to rate a shopping trip to Kohl’s, even though she had turned Location History off.
“So how did Google Maps know where I was?” she asked in a blog post .
The AP wasn’t able to recreate Shankari’s experience exactly. But its attempts to do so revealed Google’s tracking. The findings disturbed her.
“I am not opposed to background location tracking in principle,” she said. “It just really bothers me that it is not explicitly stated.”
Google offers a more accurate description of how Location History actually works in a place you’d only see if you turn it off — a popup that appears when you “pause” Location History on your Google account webpage . There the company notes that “some location data may be saved as part of your activity on other Google services, like Search and Maps.”
Google offers additional information in a popup that appears if you re-activate the “Web & App Activity” setting — an uncommon action for many users, since this setting is on by default. That popup states that, when active, the setting “saves the things you do on Google sites, apps, and services … and associated information, like location.”