As de jure segregation formed and solidified in the south:

De Jure segregation is basically legal racism that is facilitated by laws. This allowed the law enforcement officials to make it legal to not allow black people to use certain restaurants, bathrooms, water fountains, or to sit in only certain sections because of the color of their skin. The south was in favor of slavery and historically very racist, though slavery was illegal, de jure segregation allows increased levels of prejudice and racism to fester and grow.