Final answer:
Plessy v. Ferguson was a landmark Supreme Court case that legitimized the 'separate but equal' doctrine, enabling legal racial segregation until it was overturned by Brown v. Board of Education in 1954.
Step-by-step explanation:
The significance of Plessy v. Ferguson (1896) is that it established the doctrine of “separate but equal,” condoning legal racial segregation for nearly 60 years under the guise that segregated facilities did not violate the equal protection clause provided they were purportedly equal. This landmark case was a definitive moment in the perpetuation of de jure segregation and was a clear display of institutionalized racism that was not overturned until the Supreme Court's decision in Brown v. Board of Education in 1954.