The effects of immigration restrictions on innovation: lessons from the age of mass migration in the USA

Abstract The circulation of talent is threatened by the backlash against immigration and the resulting tightening of immigration policies. In this paper, we focus on the impact of the Quota Act of 1921–4 in the USA on the patenting of US counties. Using a unique dataset of historical patents, we show that counties-technologies most affected by the policy experienced a sharp decline in patenting. Our results complement the existing evidence in three ways: (1) we show that the policy had a remarkable geographical dimension, (2) the decline was also strong for breakthroughs, and (3) we generalize previous work focusing on scientists.