Also known as the Great Northward Migration and the Black Migration, this movement of more than six million African Americans from American's rural southern regions to its urban northern regions occurred over more than 50 years, from 1916 to 1970. Some historians separate this great move into two periods -- the first from 1916 to 1940, during which 1.6 million people moved from the rural south to the industrial north, and the second following the Great Depression, from 1940 to 1970, which saw more than 5 million people, many with urban skills, move north and west. Two main causes for this massive migration were poor economic conditions and racial segregation and discrimination in Southern states when Jim Crow laws were upheld. The Great Migration was historic for its sheer number, called "the largest and most rapid internal movements in history." It also brought historic change to the cities the migrants moved to, where African Americans established influential communities of their own at a time when these cities were already exerting cultural, social, political, and economic influence in the country.