Throughout history, wars have often opened new political and social avenues for marginalized groups, as happened after the United States entered World War I in April 1917. Black Americans were able to demand racial equality based on their battlefield contributions and on the home front filling industrial jobs.

In 1910, nearly 90 percent of American blacks lived in the South, four-fifths of them in rural areas. A major effect of World War I on African Americans was the increased migration of black, southern rural farm laborers northward and westward in search of industrial jobs and better social and political opportunities. This Great Migration led to the rapid growth of black urban communities in cities like New York, Chicago, St. Louis, and Los Angeles.

Military service and the slowdown of European immigration caused massive labor shortages in the North, just as war production created a demand for industrial goods. Blacks found jobs in the steel, shipbuilding, and automotive industries as well as in ammunition and meat packing factories.

There were also social and political motivations for migrating as they searched for better opportunities in life. Migration served as a way of renewing the experiences and networks that had sustained the black community during slavery and in Reconstruction, creating new centers of African-American culture in the North.

Whether their motivation was economic, political, individual, or communal, immense numbers of African Americans streamed northward. By one estimate, roughly a half-million blacks migrated to northern cities between 1915 and 1920, and between 750,000 and one million left the South in the 1920s. The African American populations of cities like Chicago and Detroit sky-rocketed.

This massive shift in population distribution dramatically altered the African-Americans culturally, politically, and socially. A new sense of African-American culture emerged. Growing black populations in urban settings created new opportunities for political activism. African Americans were even elected to important political offices. For example, Oscar De Priest, a native Alabamian and future member of Congress, became a member of the Chicago city council in 1915.

Source: World War I And The Great Migration
Office of the Historian, U.S. House of Representatives