The provision of the Civil Rights Act of 1964 that invalidated the “separate but equal” doctrine established by Plessy v. Ferguson is Title II: Public Accommodations.
Title II prohibits discrimination on the basis of race, color, religion, or national origin in places of public accommodation, which include hotels, restaurants, theaters, and other establishments that serve the public. This provision effectively counters the “separate but equal” doctrine by ensuring that all individuals have equal access to public spaces, thereby dismantling Jim Crow laws and segregation practices that stemmed from the Plessy v. Ferguson decision.