How Public Unions Became So Powerful

The Wall Street Journal reports:

The Chicago teachers strike has put Democrats in a difficult position. Teacher unions are the most powerful constituency in the Democratic Party, but their interests are ever more clearly at odds with taxpayers and inner-city families. Chicago is reviving scenes from the last crisis of liberalism in the 1970s, when municipal unions drove many American cities to disorder and bankruptcy. Where did their power come from?

An article well worth your time.