Two years after the protracted, bitter battle that pitted Wisconsin Republican Gov. Scott Walker against the state's public-sector unions and their allies, one thing is clear: Those unions are now shrinking rapidly.

The Badger State battle was over a law called Act 10 that reined in most state and local government employee unions, primarily by the ending the automatic deduction of union dues from workers' paychecks.

Before Walker's reforms, it didn't matter if, say, a city hall clerk or a public school teacher wanted to support a union or not. They had to pay if they wanted to keep their jobs. The money was taken directly out of their paychecks just as if it were a tax.

Big Labor feared -- and conservative groups hoped -- that without this legal requirement a lot of union members would simply drop out. That assumption has turned out to be correct.

According to Labor Department data, membership at Wisconsin's American Federation of State, County and Municipal Employees Council 40 -- one of AFSCME's four branches in the state -- has gone from the 31,730 it reported in 2011, to 29,777 in 2012, to just 20,488 now.

That's a drop of more than 11,000 -- about a third -- in just two years. The council represents city and county employees outside of Milwaukee County and child care workers across Wisconsin.

The drop was even starker for Wisconsin's AFSCME Council 48, which represents city and county workers in Milwaukee County. It went from 9,043 members in 2011, to 6,046 in 2012, to just 3,498 now.

The numbers came from annual filings the unions must make to the Labor Department. In other words, these membership numbers come from the unions themselves. The numbers have to hurt since the union was founded in Wisconsin.

A spokesman for Local 48 declined to discuss the figures, while spokesmen for Local 40 and AFSCME's national headquarters did not respond to requests for an interview.

To be fair, this isn't a complete portrait. The union has two other main branches in the state -- Council 11 and Council 24. According to a Labor Department spokesman, the disclosure requirements do not extend to unions that solely represent state and local government employees. Councils 40 and 48 must make the filings because they represent some private-sector employees. The other two do not.

Nevertheless, the data confirm a news report last year by the Wall Street Journal, citing confidential AFSCME sources, that Wisconsin union membership was falling by as much as half. At the time, a union official told me the story wasn't true but declined to provide alternative figures.

Why are the members dropping out? Patrick Marley, a Milwaukee Journal-Sentinel reporter and author of "More Than They Bargained For," a history of the Wisconsin fight, points out that Walker's law also limited what the unions can bargain for to just wages.

"Employees look at it from an economic standpoint," Marley said. "The value of 'buying' a union membership, so to speak, isn't what it used to be."

Of course, it is also likely that a lot of the workers didn't want to belong to a union in the first place. Exit polls show that 38 percent of union households and 29 percent of card-carrying union members voted for Walker in last year's gubernatorial recall.

During the fight over the law in 2011, pro-union protesters flooded the state Capitol, chanting "We are Wisconsin" and "This is what democracy looks like."

The message being that they represented the voice of the people. But if the unions really did represent the people the way the protesters claimed, they wouldn't have such trouble retaining their members.

Sean Higgins ( shiggins@washingtonexaminer.com) is a senior editorial writer for The Washington Examiner. Follow him on Twitter at @seanghiggins.