The great Mississippi flood of 1927 had two lasting legacies. First, it accelerated the movement of blacks out of the South in what is known as the Great Migration. Between 1920 and 1930, 1.3 million southern blacks moved north in the hopes of finding better-paying jobs and more personal liberty. The movement transformed the face of America in a decade. Before the Great Migration, only 10 percent of blacks lived outside the South. After the Great Migration, half did.