Short answers, pulled from the story.
Most definitions of the Deep South include Louisiana, Mississippi, Alabama, Georgia, and South Carolina. East Texas, North Florida, the Arkansas Delta, and parts of West Tennessee sometimes join this group.
Before 1945, the region was often called the Cotton States because cotton was its primary cash crop. Rice grew in Georgia and South Carolina while sugar dominated Louisiana during that period.
Union Army troops enabled significant roles for emancipated enslaved people and Free Blacks in state governments during Reconstruction. This incited creation of the Ku Klux Klan and similar white paramilitary groups after Federal government withdrew largely from the area following the Compromise of 1877.
Two waves of Great Migration between 1916 and 1970 moved six million African Americans northward. They escaped oppression and violence seeking better employment opportunities elsewhere.
Louisiana maintained a black majority from 1810 until about 1890. South Carolina held it until the 1920s while Mississippi lasted from the 1830s to the 1930s.