Answer:
The region south of Mason and Dixon line is the southern United states. There are 17 states in the southern US. Plantation system, black agricultural labourers an long growing season were some of the characteristics that set it apart form the other sections of US.
The unique feature of southern economy and polity was that it was completely dominated by the Whites.
The white domination lasted from 17 century till the end of second world war. White American also dominated the politics as they enacted Black codes after the civil war to restrict the freedom of African-Americans to maintain the availability of cheap labour force, Black codes were abolished during Reconstruction but their provisions were reenacted in the Jim Crow laws, these provisions ended with the Civil Rights Act of 1964.