When Ed Rendell became the mayor of Philadelphia in 1992, he started a fight with the city’s labor unions that will sound familiar to anyone who has been following the recent news from Wisconsin. In his inaugural address, Mr. Rendell, a Democrat, announced, “Philadelphia stands on the brink of total disaster.”

He told the city’s unions that they needed to accept less generous health benefits, fewer holidays and a pay freeze. The unions promised to strike. Mr. Rendell pointed out, frequently and publicly, that the city offered better benefits than private companies did. The public sided with the mayor, and on most issues, the unions eventually caved.