Thomas Frank made a splash a decade ago with a best-seller called "What's the Matter With Kansas?" In his book, Frank attempted to answer the question: Why do so many Americans — working-class Americans — vote against their economic and social interests — i.e., Republican?

I've been thinking about Frank a lot lately. Beginning with the Southern states on Super Tuesday and continuing through the important New York primary on April 19, the crucial support of black voters has created a "firewall" for Hillary Clinton against the insurgent candidacy of Bernie Sanders in the Democratic race for president. Yet Sanders is far more liberal than Clinton, and has a far better record on black issues than she does.

What's going on? Why are so many black Americans voting against their own interests — i.e., for a Democrat in Name Only?