Black Codes were Southern state laws that were created to limit the rights of freed African Americans. Some of these laws included preventing freemen from serving in the state militia, serving on juries, holding office, or voting.

Sharecropping were deals that plantation owners made with former slaves they used to own where the plantation owner provided shelter and a plot of land for the sharecropper and in return they would work for him planting crops. The sharecropper would give the crops to the landowner who would then sell them and give half of the profits to the sharecropper. Landowners would then scam the sharecroppers by increasing the amount they owed him therefore putting them in debt. 

Debt Peonage prevented sharecroppers from backing out of the deal they made with a landowner until they paid their debt turning the consensual work the sharecropper was doing into forced labor.

Nadir is referred as the worst point in American race relations where African Americans were not given their basic political and civil rights at all which were not given to them until nearly a century later during the civil rights movement.