Plessy v. Ferguson, 163 U.S. 537 (1896), was a landmark U.S. Supreme Court decision ruling that racial segregation laws did not violate the U.S. Constitution as long as the facilities for each race were equal in quality, a doctrine that came to be known as "separate but equal". The decision legitimized the many state laws re-establishing racial segregation that had been passed in the American South after the end of the Reconstruction era in 1877. Such legally enforced segregation in the south lasted into the 1960s.

Racial segregation is the separation of people into racial or other ethnic groups in daily life. Segregation can involve the spatial separation of the races, and mandatory use of different institutions, such as schools and hospitals by people of different races. Specifically, it may be applied to activities such as eating in restaurants, drinking from water fountains, using public toilets, attending schools, going to films, riding buses, renting or purchasing homes or renting hotel rooms. In addition, segregation often allows close contact between members of different racial or ethnic groups in hierarchical situations, such as allowing a person of one race to work as a servant for a member of another race. Racial segregation has generally been outlawed worldwide.