本文研究了美国移民障碍对全球知识产品的影响。我们提供了四个关键结果。首先，在诺贝尔奖获奖者和田地中，移民到美国的移民在全球知识网络中发挥着核心作用 - 代表了20-33％的前沿知识生产商。Second, using novel survey data and hand-curated life-histories of International Math Olympiad (IMO) medalists, we show that migrants to the U.S. are up to six times more productive than migrants to other countries—even after accounting for talent during one's teenage years. Third, financing costs are a key factor preventing foreign talent from migrating abroad to pursue their dream careers, particularly talent from developing countries. Fourth, certain 'push' incentives that reduce immigration barriers – by addressing financing constraints for top foreign talent – could increase the global scientific output of future cohorts by 42% percent. We conclude by discussing policy options for the U.S. and the global scientific community.