Final answer:
The Supreme Court decision that created the "separate but equal" doctrine was Plessy v. Ferguson in 1896. The case ruled that racial segregation in public facilities was constitutional as long as the facilities were equal in quality.
Step-by-step explanation:
The Supreme Court decision that created the "separate but equal" doctrine was Plessy v. Ferguson. In 1896, the Supreme Court ruled that racial segregation in public facilities was constitutional as long as the facilities were equal in quality. This decision allowed for the widespread practice of racial segregation throughout the Jim Crow era.