  The advent of geographic online social networks such as Foursquare, where
users voluntarily signal their current location, opens the door to powerful
studies on human movement. In particular the fine granularity of the location
data, with GPS accuracy down to 10 meters, and the worldwide scale of
Foursquare adoption are unprecedented. In this paper we study urban mobility
patterns of people in several metropolitan cities around the globe by analyzing
a large set of Foursquare users. Surprisingly, while there are variations in
human movement in different cities, our analysis shows that those are
predominantly due to different distributions of places across different urban
environments. Moreover, a universal law for human mobility is identified, which
isolates as a key component the rank-distance, factoring in the number of
places between origin and destination, rather than pure physical distance, as
considered in some previous works. Building on our findings, we also show how a
rank-based movement model accurately captures real human movements in different
cities. Our results shed new light on the driving factors of urban human
mobility, with potential applications for urban planning, location-based
advertisement and even social studies.
