Three decades ago this month, the economists Richard B. Freeman and James Medoff published a classic book, "What Do Unions Do?" If they wrote it today, they would have to call it "What Did Unions Do?"
Unions are dying in America. The share of private-sector workers who are union members dropped from about 35 percent in the 1950s to 6.7 percent in 2013. That gradual decline was highlighted on Friday, when workers at Volkswagen AG's Chattanooga plant voted against unionization by a count of 712 to 626.