The Contact Network of Mexico City

The most basic level of human interaction is that which happens at close proximity: conversations, physical commerce, education, sports, entertainment and transportation, are all activities that are possible through close proximity without the use of technology. The way in which people physically interact is a major component in the complexity found in human societies. Mexico City, the largest city in Mexico, is as well one of the largest cities in the world, with over 9 million inhabitants and concentrating the vast majority of government and business centers. Reconstructing the set of physical interactions between its inhabitants could lead to a better understanding of the city's complexity. Such contact network can be used for applications that range from urban planning to the spread of infectious agents. In this work, we used anonymized location data from mobile devices (cellphones) collected in the month of February 2020 to reconstruct contact networks for several days, based on physical proximity of these devices. We found that contact networks in Mexico City are very sparse, with a heavy tailed degree distribution, characterized by a largest connected component that contains between $10$ and $20\%$ of devices. We found that, while network topologies are different each day, there is no consistent difference in these between weekdays and weekends. We present this results along with the release of an anonymized network reconstructed with data from Februrary 18th, 2020, as the first description of a contact network of Mexico City.