During World War II, many American citizens migrated north, but the question is:
Why did people move to cities and industrial centers?
World War II ended the Great Depression because it created a high demand for food, textiles, rubber, metal, and many other products. The need for these products and wartime production led to economic prosperity. This increase in production also meant that many blacks could now find work in northern factories. As a result, over 2 million African Americans migrated from the South to northern cities. These people often ended up in urban ghettos, and racism was a problem faced by many. Racially fueled riots ended up killing 34 people in Detroit.
African American Migration, 1940-1945