In the post-reconstruction era most african-americans in the south had little opportunity for economic advancement, and worked mainly as

In the post-Reconstruction era and worked mainly as SHARE CROPPERS.
Share cropping system arise in the South during the post construction era as a result of the economic difficulty that was brought about by the  civil war and the abolition of slavery. Share cropping refers to the type of farming in which a family rent a plot of land from a landlord in return for a specified portion of the harvest which will be given to the landlord during the harvesting period. This type of farming was majorly practiced by former slaves who have no land of their own.

The answer is protestant reformation.