The onset of World War I spurred the “Great Migration” of African Americans from the US South, arguably the most important internal migration in US history. We create a new panel dataset of more than 5,000 men matched from the 1910 to 1930 census manuscripts to address three interconnected questions: To what extent was there selection into migration? How large were the migrants’ gains? Did migration narrow the racial gap in economic status? We find evidence of positive selection, but the migrants’ gains were large. A substantial amount of black-white convergence in this period is attributable to migration. (JEL J15, J61, N32, N92, R23)