The raucous Wisconsin debate over collective bargaining may be ugly at times, but it has been worth it for the splendid public education. For the first time in decades, Americans have been asked to look under the government hood at the causes of runaway spending. What they are discovering is the monopoly power of government unions that have long been on a collision course with taxpayers. Though it arrived in Madison first, this crack-up was inevitable.

We first started running the nearby chart on the trends in public and private union membership many years ago. It documents the great transformation in the American labor movement over the latter decades of the 20th century. A movement once led by workers in private trades and manufacturing evolved into one dominated by public workers at all levels of government but especially in the states and cities.

The trend is even starker if you go back a decade earlier. In 1960, 31.9% of the private work force belonged to a union, compared to only 10.8% of government workers. By 2010, the numbers had more than reversed, with 36.2% of public workers in unions but only 6.9% in the private economy.

The sharp rise in public union membership in the 1960s and 1970s coincides with the movement to give public unions collective bargaining rights. Wisconsin was the first state to provide those rights in 1959, other states followed, and California became the biggest convert in 1978 under Jerry Brown in his first stint as Governor. President Kennedy let some federal workers organize (though not collectively bargain) for the first time in 1962, a gambit to win union support for his re-election after his cliffhanger victory in 1960.

It's important to understand how revolutionary this change was. For decades as the private union movement rose in power, even left-of-center politicians resisted collective bargaining for public unions. We've previously mentioned FDR and Fiorello La Guardia. But George Meany, the legendary AFL-CIO president during the Cold War, also opposed the right to bargain collectively with the government.