White people and Black people were in separate cars and required them to sit separately.
Plessy
Plessy argues that the 14th Amendment says that the states may not “ deny to any person within their jurisdiction the equal protection of the laws.”
He argued that requiring black people to sit separately from white people implied that blacks were inferior to whites, and therefore unequal.
The Supreme Court disagreed. It saw separate train cars as an issue of social equality, not political or legal equality. It said separating the races did not take away civil or political rights.
Plessy V. Ferguson
Plessy V. Ferguson was monumental because it essentially established the constitutionality of racial segregation.