In the last years of his life, following the passage of the 1964 Civil Rights Act and 1965 Voting Act, Martin Luther King’s speeches and writings took on increasingly radical tones. By 1967, he was telling organizers that “the movement must address itself to the question of restructuring the whole of American society” and “the problems of racial injustice and economic injustice cannot be solved without a radical redistribution of political and economic power.”

King’s commitment to pushing beyond legal rights to win full social, economic, and political equality had long animated him. The idea that, as he put it in 1967, “something is wrong with the economic system of our nation . . . something is wrong with capitalism,” was not new. Yet it remains remarkable that, by the end of the 1960s, the most important leader of the most successful US social movement of the twentieth century — one that toppled a vicious social order doggedly backed by some of the most powerful elites in American society — was a democratic socialist.

That fact, attested in a library’s worth of King biographies and scholarship on the civil rights movement, should be something of an obsession for the contemporary left. Yet today, socialists in the United States are often more apt to study revolutions in Russia or China than the massive social transformation in our own country just sixty years ago.