Final answer:
Lyndon Johnson, Kennedy's successor as President, played a major role in passing the Civil Rights Act of 1964 and implementing social programs to improve lives and transform society.
Step-by-step explanation:
Lyndon Johnson, Kennedy's successor as President, had been on the national stage since 1937. After being sworn in as the thirty-sixth President after the assassination of Kennedy, Johnson stayed true to Kennedy's plan. He successfully persuaded Southern Democrats to stop blocking the passage of the Civil Rights legislation, and signed the Civil Rights Act of 1964 into law. Additionally, Johnson's social programs and commitment to civil rights improved the lives of many people and transformed society.