Shanghai Study Shows City Borders May Not Match Real Travel Flow

Officials in Shanghai picked a rule that split the city into zones using its official borders. This way is simple but can put very different neighborhoods under the same risk tag. The rule works fast for officials, but it can hide the true way people move around the city.

The team examined over a billion phone travel records from two short periods in 2019 and 2020. Each record shows where a person started a trip and where they ended it each day. The data came from China Unicom, the biggest phone carrier in the country.

They wanted to see if people’s travel matched the border rule or a circle rule that uses a set distance from a point. They also checked if the groups that formed from the travel data lined up with the official districts. When they looked at the patterns, they saw that many neighborhoods moved together even if they were in different districts.

The results showed the travel groups often did not line up with the official districts. That means the border rule can mix places with different travel habits. A circle rule may keep nearby areas together while still counting far‑away spots that travel often. Because of this, the city might need a new rule that follows the real travel flow instead of the drawn border.