Dongguan is a city in Guangdong Province in southern China, about 100 kilometers north of Hong Kong. It is a bustling city of factories, hotels, restaurants, and ... the sex trade. A couple of days ago, 6,000 police conducted a massive sweep. They raided 200 saunas, 672 foot massage parlors, 362 karaokes, and 694 sites of other types of “entertainment”. 162 people were taken away for questioning.
A huge number of people fled from Dongguan for a number of neighboring cities. The exodus was captured vividly by the traces left by the mobile devices. The largest number fled towards Hong Kong. The owners of these mobile devices probably did not expect that their movements could be traced this way.