International collaborations and the patenting intensity of US inventors

Knowledge transfer is fostered not only by the geographic co-location of firms and individuals, but also by networks of collaborations. In recent decades, the number of patents co-invented between inventors located in different countries has increased steadily. This paper tests the hypothesis that collaborating with inventors residing abroad provides to the individual innovator novel yet complementary knowledge, which can be recombined to generate further innovation. Empirically, using a sample of US-based inventors and their patents filed with the USPTO between 1980 and 2020, I estimate the effects of prior collaborations with foreign inventors on inventor’s patenting intensity, measured by the annual count of patents granted. Controlling for a wide array of fixed effects at the individual, firm, technology, city, and time levels, I find that prior international collaborations significantly increase an inventor's patenting intensity. These findings are robust across subsamples, independent variables, and alternative model specifications. The results suggest that the globalization of inventive activity complements local agglomeration and network effects as a key driver of patenting intensity.