What would have happened if Plessy v. Ferguson had not been overturned by the Supreme Court?

The Supreme Court's decision in 1896 in the case of Plessy v. Ferguson established the constitutionality of state sponsored segregation based on the pernicious legal doctrine known as "Separate But Equal." This doctrine gave Southern states the authority to segregate blacks and whites for purposes of schooling, housing, and even bathroom usage. The entire social and political landscape of the post-Reconstruction South hinged on the ability of whites to corral freed African Americans into black neighborhoods, where housing, education and job opportunities were substandard, and far worse than those for whites.

If Brown v. The Board of Education had not overturned Plessy v. Ferguson in 1954, the Civil Rights Movement would have likely been delayed even further. Brown v. The Board of Education ruled that separating black and white students into separate schools could only result in black students having a poorer quality of education; the ruling correctly recognized that school funding was based on property taxes, and the revenue from substandard housing in black neighborhoods was significantly less than the revenue collected from wealthier white neighborhoods, which in turn guaranteed white students better facilities, teachers and books.  Brown v. the Board of Education stated that segregating students based on race could only result in inequality.

The ripple effects of that ruling soon led to the desegregation of universities and housing, and set up the much larger showdown between Martin Luther King's Southern Leadership Conference and its liberal allies and the racist, backward looking leaders of southern states, cities and schools. The upheaval that followed led to a national movement that culminated in federal Civil Rights Act (1964) and Voting Rights Act (1965), which gave equal protection under the law to all citizens of the United States, regardless of race.

The decision of the Supreme Court to strike down Plessy v. Ferguson made it possible for a new generation of black leaders to get good educations, and enter the medical and legal professions (among others) in much high numbers. This led to a larger black middle and upper-middle class, who in turn exercised their franchise in lasting, powerful ways. If Plessy v. Ferguson been been upheld, we might today still live in a semi-Apartheid state, as South Africans did until the 1990s. Our economy, culture and standing in the world would have suffered immensely.