In the 1960s, Mississippi was the heart of white southern resistance to the civil-rights movement. To many, it was a backward-looking society of racist authoritarianism and violence that was sorely out of step with modern liberal America. White Mississippians, however, had a different vision of themselves and their country, one so persuasive that by 1980 they had become important players in Ronald Reagan's newly ascendant Republican Party. In this...