  This paper studies international migration from a complex-network
perspective. We define the international-migration network (IMN) as the
weighted-directed graph where nodes are world countries and links account for
the stock of migrants originated in a given country and living in another
country at a given point in time. We characterize the binary and weighted
architecture of the network and its evolution over time in the period
1960-2000. We find that the IMN is organized around a modular structure
characterized by a small-world pattern displaying disassortativity and high
clustering, with power-law distributed weighted-network statistics. We also
show that a parsimonious gravity model of migration can account for most of
observed IMN topological structure. Overall, our results suggest that
socio-economic, geographical and political factors are more important than
local-network properties in shaping the structure of the IMN.
