How long did great migration take​

The Great Migration was the movement of some six million African Americans from rural areas of the Southern states of the United States to urban areas in the Northern states between 1916 and 1970.

Explanation:

The Great Migration was the relocation of more than 6 million African Americans from the rural South to the cities of the North, Midwest and West from about 1916 to 1970.

norsemen from northern countries had made earlier journeys