a new firm level dataset to study the network of formal firm linkages within
and across 52 aerospace clusters in North America and Europe over the
period 2002-2014. Applying community structure detection techniques, we find
that the structure of the overall network has changed over time. We organize
sub-networks by linkage type and find two important trends in their evolution.
First, new linkages in the vertical buyer-supplier sub-network are generally
formed in a hierarchical hub-and-spoke fashion, whereas new links in the
horizontal partnership sub-network are generated in a more decentralized and
cohesive manner. Second, the geographical scope of new linkages is different,
with vertical buyer-supplier and investment linkages moving increasingly trans-local
and partnership linkages becoming more localized. Taken together, our findings
suggest that the overall network is evolving from a geographically partitioned
community structure to a hierarchical community structure that is stratified
along value chain stages.