THE GREAT MIGRATION (1915-1960)
from the Website BLACK PAST.ORG: Remembered & Reclaimed
.....The first large movement of blacks occurred during World War I, when 454,000 black southerners moved north. In the 1920s, another 800,000 blacks left the south, followed by 398,000 blacks in the 1930s. Between 1940 and 1960 over 3,348,000 blacks left the south for northern and western cities.