Agglomeration of invention in the Bay Area: Not just ICT

We document that the Bay Area rose from 4% of all successful US patent applications in 1976 to 16% in 2008. This is partly driven by the increase in the prevalence of information and communication technology; however, even for patents unrelated to information and communication technology, we see a disproportionate increase in the share of all US patents from the Bay Area. We interpret this to suggest that there has been a trend to coagglomeration in invention across technologies. We explore several possible explanations for this trend, and conclude that the size of firm or simple measurement error cannot explain it. JEL Code: R12, O31 * Max Koven and Yasin Ozcan provided excellent research assistance. We thank seminar participants at the University of Toronto for helpful comments. Avi Goldfarb thanks SSHRC for research support.