Jackson, Miss. — More than 60 years after a white supremacist assassinated civil rights leader Medgar Evers, his daughter still sees the same strain of political violence at work in American society. “It’s painful,” said Reena Evers-Everette. “It’s very painful.” Evers-Everette was 8 years old when her father, a field secretary for the NAACP, was shot to death in the driveway of his home in Jackson, Mississippi. Medgar Evers in 1958. Francis H. Mitchell / AP A few months after Evers’ killing in 1963, President John F. Kennedy was gunned down. The deaths of civil rights leaders Martin Luther King...