Cities of a feather flock together: a study on the synchronization of communication between Italian cities

Due to the rise of communication technologies and economic globalization, modern large cities are becoming more and more interconnected and this phenomenon leads to an increasing synchronization in activities and communication patterns. In our work, we explore the communication synchronization between 76 Italian cities of different sizes by using mobile phone data. Our results show that both the spatial distance and the size of the city influence the synchronization: larger cities are more similar to larger cities in communication rhythms than medium cities are to medium cities, and medium cities are more similar to medium cities than smaller cities are to smaller cities. Furthermore, for all the cities' sizes we observe a drift in similarity due to spatial distance. Interestingly, the drift due to distance over similarity is less strong in large cities, that act as gateway nodes for the Italian economical system, hence having an emerging strongly connected and synchronized network, than for medium and small cities, that are more bounded to local industries. Finally, our results also show that highly synchronized cities are richer and more attractive for foreign-born population.