1950s: African Americans are still moving from the rural South to big cities in the North, hoping for good jobs and equal opportunity. Segregation, racism and a weak economy hinder many of their efforts.

2000s: The Great Migration is over, and is reversing. Since the 1960s, many African Americans, especially from the middle class, have left the North and moved to large cities in the South.

1950s: Harlem is in economic decline as middle-class African Americans move out, leaving only the poor behind. Half of all housing units are unsound.

2000s: Harlem is gradually being gentrified as middle- and upper-class African Americans return. They are buying and fixing up formerly run-down homes, causing housing prices to rise dramatically. Former President Bill Clinton opens an office in Harlem, and wealthy black business owners are opening businesses there.

1950s: Public schools in the South are segregated...