But unions, he says, have been buffeted by forces beyond their control: Improved productivity and technology have reduced the number of workers needed. Non-union employers have expanded in right-to-work-states. Companies have waged aggressive, successful campaigns to keep unions out. Plant closings make it almost impossible to replenish the number of union members lost.Also, potential recruits are wary. "For most workers, joining a union is a risky deal and it has very little payback," Chaison says. "Most unions have not put their hearts and treasuries into organizing. It's so difficult and the payoff is minimal." Zimmick knows firsthand. His local tried to organize workers at an auto supplier two years ago. The company, he says, responded by giving employees raises. "They said, 'Don't talk to those union guys. We're going to take care of you.'" The campaign didn't get to the vote stage. The number of elections to certify unions has dropped dramatically. In fiscal year 2012, there were about 1,200 with more than 83,000 eligible voters, according to the National Labor Relations Board. In 1971, there were more than 7,500 with nearly 550,000 eligible voters. The silver lining for union organizers: Approval rates have been near or above 60 percent since 2006. In contrast, they were just half in 1990. In the heyday of unions in 1950, though, three of four workers voting wanted to sign on. Union membership declined to 11.3 percent of the workforce last year from 11.8 percent in 2011, according to federal statistics. Especially notable was a loss in the private sector, even as the economy created 1.8 million jobs. "I chuckle every time I hear the words Big Laborâ¿¿ 6.6 percent is not big," says Jefferson Cowie, a Cornell University labor historian, referring to the share of private-sector workers in unions. And yet, unions still have considerable muscle, capable of raising tens of millions of dollars for political campaigns â¿¿ largely for Democrats â¿¿ and getting out the vote. Last fall, the AFL-CIO announced it had registered more than 450,000 new voters from union households in the previous 18 months.