The Big Sort

Robert Samuelson reports that Americans are increasingly living near people who think like them:

[The researchers] classified counties as politically lopsided if one candidate won by 20 percentage points or more. Their findings are stunning. In the 1960 Kennedy-Nixon election, a virtual dead heat, 33 percent of counties qualified. By 2000, also a dead heat, that was 45 percent. In 2004, it was 48 percent.