In this paper, I investigate the effects of short- and long-distance commuting flows on the spatial diffusion of ideas or practices, through a stylized computational model of two spatial units. Located at fixed places within each spatial unit, individuals interact exclusively with their spatial neighbors. Commuters live and work at different locations, therefore, alternate between two different neighborhoods. The expansion diffusion occurs by local contagion: the probability that any individual adopts the diffusion item is increasing on the adopting neighbors she/he observes. Commuting flows affect in a fundamentally way the speed of the diffusion process. Short-distance commuting flows always accelerate the diffusion within a spatial unit. The effect of long-distance commuting flows depends on the spatial distribution of workplaces in the destination city. If commuters’ workplaces are uniformly dispersed, both cities’ adoption dynamics tend to be coupled. If, instead, workplaces are concentrated in some area, the diffusion in the destination city is much more slow paced than in the origin spatial unit.
