This week at the Book Club, Bill Bishop is joining us to discuss The Big Sort: Why The Clustering of Like-Minded America is Tearing Us Apart. He opens the discussion with a simple calculation: "In 1976, about a quarter of the voters lived in a county where either Jimmy Carter or Gerald Ford won by 20 percentage points or more. The number of people living in landslide communities increased steadily over the next seven presidential elections. And by 2004, in another very close vote, nearly half of all voters lived in one of these landslide communities."