Privacy and Surveillance in Location Data

In December 2019, New York Times journalists Stuart A. Thompson and Charlie Warzel published "One Nation, Tracked," an investigation built on a leaked dataset of roughly 50 billion location pings collected from more than 12 million American smartphones over several months. The reporting demonstrated that even data marketed by brokers as "anonymized" could be used to re-identify specific individuals — including, in one striking example, tracing a single device's movements from a residence to a workplace and back — simply by cross-referencing repeated visits to distinctive, uncommon locations, a finding that reshaped public debate over what "anonymized" location data really protects.