America’s celebrations of Martin Luther King, Jr. typically focus on his civil rights activism: the nonviolent actions that led to the Civil Rights Act of 1964 and the Voting Rights Act of 1965.

The last few years of King’s life, by contrast, are generally overlooked. When he was assassinated in 1968, King was in the midst of waging a radical campaign against economic inequality and poverty, while protesting vigorously against the Vietnam War. (...)