Every minute of every day, everywhere on the planet, dozens of companies — largely unregulated, little scrutinized — are logging the movements of tens of millions of people with mobile phones and storing the information in gigantic data files. The Times Privacy Project obtained one such file, by far the largest and most sensitive ever to be reviewed by journalists. It holds more than 50 billion location pings from the phones of more than 12 million Americans as they moved through several major cities, including Washington, New York, San Francisco and Los Angeles.
Each piece of information in this file represents the precise location of a single smartphone over a period of several months in 2016 and 2017. The data was provided to Times Opinion by sources who asked to remain anonymous because they were not authorized to share it and could face severe penalties for doing so. The sources of the information said they had grown alarmed about how it might be abused and urgently wanted to inform the public and lawmakers.