Decoupling geographical constraints from human mobility.

Driven by access to large volumes of movement data, the study of human mobility has grown rapidly over the past few decades. The field has shown that human mobility is scale-free, proposed models to generate scale-free moving distance distributions and explained how the scale-free distribution arises. It has not, however, explicitly addressed how mobility is structured by geographical constraints, such as how mobility relates to the outlines of landmasses, lakes and rivers and the placement of buildings, roadways and cities. On the basis of millions of moves, we show how separating the effect of geography from mobility choices reveals a power law spanning five orders of magnitude. To do so, we incorporate geography via the pair distribution function, which encapsulates the structure of locations on which mobility occurs. By showing how the spatial distribution of human settlements shapes human mobility, our approach bridges the gap between distance- and opportunity-based models of human mobility.