The Great Migration of African-Americans from the rural South to Northern urban centers lasted from 1916 until 1970, hitting a peak in the 1920s. For example, Detroit's African-American population, which had increased by 600 percent during World War I, increased another 200 percent between 1920 and 1930. This mass exodus from the segregated South made problems of social and political inequality national issues, paving the way for the Civil Rights Movement of the '60s.

The Pull North

Life in the South held little promise for African-Americans in the years following World War I. Jim Crow laws enforced racial segregation, and black schools were poorly funded. In rural areas, many African-Americans had little choice but to work as sharecroppers -- a life with little hope of prosperity. Meanwhile, companies in the industrialized North needed factory workers as a result of increased production and a shortage of labor caused by the military draft. Factory owners looked south, sending recruiters to entice blacks north with the promise of good-paying jobs and low-cost housing. As racial violence intensified in the South with the rise of the KKK in the 1920s, more African-Americans began to take those recruiters up on their offers and start new lives in cities including Chicago, New York and Detroit.

Changing Demographics

In the early decades of the Great Migration, the racial makeup of major Northern cities changed dramatically. While Northern states didn't have legal segregation, discrimination often sequestered African-American migrants to crowded inner city neighborhoods. For example, the previously all-white neighborhood of Harlem in New York City became home to more than 200,000 African-American migrants by the 1920s. In the years during and after World War I, Chicago's African-American population increased by nearly 150 percent, Philadelphia's by 500 percent. Although urban life held its own challenges, many migrants found that people in the Northern cities were relatively indifferent to them, and this freedom inspired a burgeoning interest in political activism as well as artistic and cultural expression.

A New Cultural Identity

In Harlem particularly, a literary, artistic and intellectual movement that became known as the Harlem Renaissance kicked off in the 1920s. Migrants such as Langston Hughes, Zora Neale Hurston and Jessie Redmon Fauset began a literary exploration of African-American life and experience. Migration caused a political awakening for many African-Americans, giving them new perspectives of the race's potential role in American society. The older generation, including Howard University philosophy professor Alain Locke, observed and mentored these younger migrants. For Locke, the movement in Harlem represented a "spiritual coming of age" that transformed "social disillusionment to race pride."

That Chicago Sound

Like many other Northern cities, Chicago's population exploded during the Great Migration. Many of Chicago's migrants came from the Mississippi Delta, particularly after the Great Flood of 1927 destroyed homes and ruined crops, sending thousands of African-Americans north in search of new lives. From 1920 through 1930, the African-American population of Chicago increased from 109,458 to 233,903. Some of these migrants brought musical traditions with them, such as the fabled Delta blues. In the urban environment, musicians became more informed about the instruments they played and gained access to other musical styles. Louis Armstrong, who migrated to Chicago in 1922, helped bring the jazz sound to mainstream America.