One unit tended effect of emancipation and reconstruction on southern society was

One unintended effect of emancipation and reconstruction on southern society was the rising tensions between the races.

During the Reconstruction Era, the Thirteenth, Fourteenth and Fifteenth Amendments abolished slavery, protected the black people's rights and discrimination, despite all of this, there was still social conflict between races. Tensions rose between freed slaves and their former slaveholder. Former slaveholders now had the duty to negotiate about wages with who were their slaves before. Suddenly, emancipated slaves were protected by law and had rights they didn't have before, but American society still had a long way to run before race equality became the norm.  

the answer is migration