In one town, one teenager messaged a friend that two boys were going to have a fight. In 15 minutes, one hundred teenagers drove to the address.
Imagine if people were organizing an attack, or rioting and looting.
That's what police on the street have to face with civilians armed with cell phones.
An estimated 2.87 billion cell phone users worldwide have changed policing, exposed policing, and they have done the same for protesting.
Law enforcement, and especially federal law enforcement, know how to identify and track individuals by their phones. Using cell phone data, police can literally track a person from a protest to their home.
On the other hand, organized demonstrators are well informed about ways to set their phones to avoid police surveillance and hundreds of main stream publications on the internet give them step-by-step instructions. They can use cell phones to avoid police, stage mob action at stores or buildings, riot, loot, or just gather peacefully at a park.
What few people know is that when cell phones are used in demonstrations, lots of people are listening.
Political groups are buying data on potential voters. In June, aided by a $2 million donation from former New York Mayor Michael Bloomberg, a firm called The Collective, which seeks to elect African-Americans to office, gathered data on protesters in five cities to see where to concentrate their voter registration efforts, according to the Wall Street Journal. One group targeted ads to Facebook users whose cell phones were present at demonstrations.
The Republicans do the same with data from Trump rallies.