Passage: "The Great Migration refers to the movement of about six million African Americans from the rural South to cities in the North, Midwest, and West between 1916 and 1970. Many sought better economic opportunities and an escape from segregation. The migration reshaped the populations and cultures of major American cities." According to the passage, roughly how many people took part in the Great Migration?

1. About six hundred thousand
2. About six million
3. About sixty million
4. The number is unknown