JeffreyBaker, Southern Univeristy Museum of Art, 610 Texas, Shreveport, a photo by trudeau on Flickr.
The Great Migration was the movement of 2 million blacks out of the Southern United States to the Northeast, Midwest and West from 1910 to 1930, says Wikipedia.
African Americans migrated to escape racism and prejudice in the South, as well as to seek jobs in industrial cities.
Some historians differentiate between a First Great Migration (1910–30), numbering about 1.6 million migrants, and a Second Great Migration (1940 to 1970), in which 5 million or more people moved and to a wider variety of destinations.
From 1965–70, 14 states of the South, especially Alabama, Louisiana and Mississippi, contributed to a large net migration of blacks to the other three cultural (and census-designated) regions of the United States.
By the end of the Second Great Migration, African Americans had become an urbanized population. More than 80 percent lived in cities. Fifty-three percent remained in the South, while 40 percent lived in the North and 7 percent in the West.
A reverse migration has gathered strength since 1965, dubbed the New Great Migration, the term for demographic changes from 1965 to the present which are a reversal of the previous 35-year trend of black migration within the United States.