Few people would dispute that the civil rights movement of the 1950s and 1960s was perhaps the most significant domestic event in U.S. history in the last half of the 20th century.

Among other things, the laws that came out of the movement granted voting rights to millions of Americans who did not have them, outlawed to some extent discrimination in the workplace, and ended segregation in public schools and many other facilities.

Besides expanding the voting rolls by millions of people, the civil rights movement also had (and continues to have) a huge – though often unseen and underestimated –...