Clusters and the Great Recession. Michael E. Porter, February 23, 2015, Paper. “This paper evaluates the role of clusters in the resilience of regional employment to economic downturns. Agglomeration economies arise in regions specialized in clusters (groups of closely related and complementary industries operating within a particular region), and could mitigate the effects of economic recessions. However, an alternative hypothesis is that cluster specialization could propagate negative shocks among related industries, increasing the impact of recessions. This paper explores these issues over the period of the Great Recession...” Link