Final answer:
Governor Ross Barnett defied the Supreme Court on September 20 by attempting to block James Meredith, an African American student, from enrolling at the University of Mississippi, in an act against integration during the Civil Rights Movement.
Step-by-step explanation:
On September 20, 1962, Mississippi Governor Ross Barnett openly defied the U.S. Supreme Court's desegregation order by attempting to block James Meredith, an African American student, from enrolling at the University of Mississippi (Ole Miss). In a symbolic and confrontational act, Barnett stood in the doorway of the university registrar's office, physically obstructing Meredith's entry.
This event mirrored the resistance to integration seen in other Southern states, reminiscent of Governor George Wallace's "Stand in the Schoolhouse Door" in Alabama. Barnett's actions highlighted the deep-seated opposition to desegregation in Mississippi, becoming a significant moment in the Civil Rights Movement. The incident emphasized the ongoing challenges and confrontational politics surrounding racial integration during this transformative period in American history.