When was the Great Migration?

The Great Migration was the movement of 6 million African Americans out of the rural Southern United States to the Northeast, Midwest, and West from 1910 to 1970. Some historians differentiate between the first Great Migration (1910-1930), numbering about 1.6 million migrants who left mostly rural areas to migrate to northern and midwestern industrial cities, and, after a lull during the Great Depression, a Second Great Migration (1940 to 1970), in which 5 million or more people moved, including many to California and various western cities. i got it from wikipedia