Answer;
African Americans left the South in large numbers to work in war-related industries.
Step-by-step explanation;
-As the countries of Europe recovered from World War II, they again became attractive destinations for potential migrants and opened their doors to immigrants to help rebuild their economies.
-Furthermore, during the post-war period, technological improvements in land and air travel decreased the cost of migration. Emigration from developing countries to Western countries expanded rapidly as incomes in the developing world rose enough to make emigration feasible, but not enough to make it moot.
-During the Great Migration Between 1910 and 1920, hundreds of thousands of African-Americans had uprooted themselves from their homes in the South and moved north to the big cities in search of jobs