Research also suggests that diversity has a net positive effect on productivity and economic prosperity. A study by Nathan Nunn, Nancy Qian and Sandra Sequeira found that the Age of Mass Migration (1850–1920) has had substantially beneficial long-term effects on U.S. economic prosperity: "locations with more historical immigration today have higher incomes, less poverty, less unemployment, higher rates of urbanization, and greater educational attainment. The long-run effects appear to arise from the persistence of sizeable short-run benefits, including earlier and more intensive industrialization, increased agricultural productivity, and more innovation." The authors also find that the immigration had short-term benefits: "that there is no evidence that these long-run benefits come at short-run costs. In fact, immigration immediately led to economic benefits that took the form of higher incomes, higher productivity, more innovation, and more industrialization."