Jim Crow Laws: These were state and local laws enacted in Southern states after Reconstruction that enforced racial segregation, including in schools.
Separate but Equal Doctrine: This legal doctrine allowed for racially segregated facilities as long as they were deemed "equal" in quality. It was overturned by Brown v Board of Education.
Plessy v Ferguson: In this landmark case, decided before Brown v Board of Education, it was ruled that racial segregation was constitutional as long as separate facilities were equal.