Final answer:
Plessy v. Ferguson was the 1896 Supreme Court case that upheld "separate but equal" doctrine for racial segregation in response to a Louisiana law requiring separate train cars for white and African American passengers.
Step-by-step explanation:
The Supreme Court decision that made the claim in response to a state requiring separate train cars for white and African American passengers was Plessy v. Ferguson, which took place in 1896. This legal case upheld the principle of "separate but equal", stating that de jure segregation did not violate the equal protection clause of the 14th Amendment as long as the segregated facilities provided to both races were of equal quality. The case stemmed from an 1892 incident where Homer Plessy, a man of mixed racial heritage, sat in a whites-only car of the Louisiana railroad to challenge the segregation laws of the time. His subsequent arrest led to a legal battle that culminated in the Supreme Court's decision. The doctrine of "separate but equal" remained in place until it was explicitly overturned by Brown v. Board of Education in 1954, which ruled that separate educational facilities were inherently unequal.