This paper shows that the growing regional disparities in the U.S. since 1980 can be explained by firms endogenously responding to a skill-biased technology shock.With the introduction of a new skill-biased technology that is high fixed cost but low marginal cost, firms endogenously adopt more in big cities, cities that offer abundant amenities for high-skilled workers, and cities that are more productive in using high-skilled labor.In cities with more adoption, small and unproductive firms are more likely to exit the market, increasing the equilibrium rate of turnover or business dynamism-a selection effect similar to Melitz (2003).Differences in technology adoption and selection account for three key components of the growing regional disparities known as the Great Divergence: (1) big cities saw a larger increase in the relative wages and supply of skilled workers, (2) big cities saw a smaller decline in business dynamism, and (3) firms in big cities invest more intensively in Information and Communication Technology (ICT).