We show a causal impact of immigration on innovation and dynamism in US counties. To identify the causal impact of immigration, we use 130 years of detailed data on migrations from foreign countries to US counties to isolate quasi-random variation in the ancestry composition of US counties that...

In a general equilibrium product-cycle model, lower trade barriers increase Southern purchasing power, which lifts long-run growth by increasing the profit from innovation. In the short run, factors of production must be reallocated inside firms, which lowers the opportunity cost of innovation,...