Abstract:

We characterize the contribution of immigrants to US innovation, both through their direct productivity as well as through their indirect spillover effects on native inventors. To do so, we link patent records to a database containing the first five digits of millions of Social Security Numbers (SSN). By combining the first five digits of SSN together with year of birth, we identify whether individuals are immigrants based on the age at which their Social Security Number is assigned. We establish several results. We find that over the course of their careers, immigrants are more productive than natives, as measured by number of patents, patent citations, and the economic value of these patents. Immigrant inventors are more likely to rely on foreign technologies, to collaborate with foreign inventors, and to be cited in foreign markets, thus contributing to the importation and diffusion of ideas across borders. Using an identification strategy that exploits premature deaths, we find that immigrants create greater positive spillovers and contribute more to team-specific capital than natives. A simple decomposition suggests that 30.4% of aggregate US innovation since 1976 can be attributed to immigrants, with their indirect spillover effects accounting for more than twice their direct productivity contribution.