This paper evaluates the role of regional cluster composition in regional industry performance. On the one hand, diminishing returns to specialization in a location can result in a convergence effect: the growth rate of an industry within a region may be declining in the level of economic activity of that industry. At the same time, positive spillovers across complementary economic activities can provide an impetus for agglomeration: the growth rate of an industry within a region may be increasing in the “strength” (i.e., relative presence) of related industries. Building on Porter (1998, 2003), we develop a systematic empirical framework to analyze the role of regional clusters – groups of closely related industries operating within a particular region – in the growth of regional industries. We exploit data from the US Cluster Mapping Project to examine the effects of agglomeration within regional clusters after controlling for convergence at the region-industry level. Our findings suggest that industries located in a strong cluster register higher employment and patenting growth. Regional industry growth also increases with the strength of related clusters in the region and with the strength of similar clusters in adjacent regions. We also find evidence of the complementarity between employment and innovation performance in regional clusters: both the initial employment and patenting strength of a cluster have a separate positive effect on the employment and patenting growth of the constituent industries. Finally, we find that new regional industries emerge where there is a strong cluster. These findings are consistent with multiple types of externalities arising in clusters, including knowledge, skills, and input–output linkages.
