Opinion | How to Track President Trump

The device’s owner was easy to trace, revealing the outline of the person’s work and life. The same phone pinged a dozen times at the nearby Secret Service field office and events with elected officials. From computer screens more than 1,000 miles away, we could watch the person travel from exclusive areas at Palm Beach International Airport to Mar-a-Lago.
The meticulous movements — down to a few feet — of the president’s entourage were recorded by a smartphone we believe belonged to a Secret Service agent, whose home was also clearly identifiable in the data. Connecting the home to public deeds revealed the person’s name, along with the name of the person’s spouse, exposing even more details about both families. We could also see other stops this person made, apparently more connected with his private life than his public duties. The Secret Service declined to comment on our findings or describe its policies regarding location data.