The cross-country diffusion of technology is a central driver of productivity growth and economic convergence. This paper provides novel evidence on the role of out-migration as a channel of technology transfer from destination to origin countries. We construct an individual-level dataset linking four million British immigrants in the US to the UK census (1870-1930) and digitize the universe of British patents granted in the nineteenth century. Using a shift-share design that leverages shocks to US innovation, together with text analysis of patents, we document that migration ties facilitated the diffusion of US technology to the UK. Return migration was an important driver of this effect. However, migrants' social networks at home fostered technology transfer even in the absence of physical return.

Between 1920 and 1921, Italian emigration to the United States dropped by 85% after the Emergency Quota Act, a severely restrictive immigration law, was passed by the US Congress. Using newly digitized data from Italian historical censuses in a difference-in-differences setting, we leverage variation in exposure across Italian districts to this large restriction on human mobility. More exposed districts display a sizable population increase. Moreover, the policy substantially hampered the adoption of labor-saving technology. Consistent with directed technology adoption theory, manufacturing employment increased markedly, and evidence suggests that "missing migrants," whose migration was inhibited by the Act, drive this result.

How do societies respond to adversity? We provide novel evidence focusing on the reaction to the 1918-1919 influenza pandemic in the United States. We document that counties hit harder by the pandemic became both more religious and more scientific. We investigate the underlying mechanism, examining how individuals within counties reacted to the shock. We uncover heterogeneous responses, with religion and science acting as substitute ways of coping with the pandemic. Facing adversity widened the distance in religiosity between science-oriented individuals and the rest of the population and increased the polarization of religious beliefs.

I examine how the Progressive-era Settlement movement impacted immigrant assimilation in the US between 1880 and 1940. Settlements provided job training, childcare, and language classes to immigrants in urban areas. Using an individual-level triple difference that leverages across-neighborhood, cross-cohort, and over-time variation in settlement exposure, I find that settlements had positive labor-market effects for men but not for women and increased segregation. These responses persisted into the generation exposed to settlements during childhood. The heterogeneous effects of settlements partly stemmed from increased fertility that excluded women from labor markets, particularly among immigrants from countries with more conservative gender norms.