Cities are characterized by concentrating population, economic activity and services. However, not all cities are equal and a natural hierarchy at local, regional or global scales spontaneously emerges. In this work, we introduce a method to quantify city influence using geolocated tweets to characterize human mobility. Rome and Paris appear consistently as the cities attracting most diverse visitors. The ratio between locals and non-local visitors turns out to be fundamental for a city to truly be global. Focusing only on urban residents' mobility flows, a city to city network can be constructed. This network allows us to analyze centrality measures at different scales. New York and London play a predominant role at the global scale, while urban rankings suffer substantial changes if the focus is set at a regional level.
@article{arxiv.1501.07788,
title = {Human diffusion and city influence},
author = {Maxime Lenormand and Bruno Gonçalves and Antònia Tugores and José J. Ramasco},
journal= {arXiv preprint arXiv:1501.07788},
year = {2015}
}