"The worker centers are obviously springing up to address an unmet need in geographic areas or in particular industries," said Craig Becker, general counsel at the AFL-CIO.
The AFL-CIO is also seeking to expand its Working America affiliate, which has more than 3 million members sympathetic to unions, but don't work under collective bargaining agreements and pay only token dues or nothing at all.
As businesses have become more aggressive and successful at battling union organizers, unions are also increasingly targeting non-traditional workers for membership. In Minnesota, lawmakers this year authorized unions to try organizing some 12,700 home day care providers who take care of children subsidized by the state. Similar measures affect home care workers in Vermont and Rhode Island.
Unions claim collective bargaining will help home care workers earn better wages and benefits for health care and retirement. But critics say the added costs will be borne by parents who can't afford it.
Unions also hope to target thousands of graduate students at private universities. Labor advocates are urging the National Labor Relations Board to overturn a 2004 decision that said graduate assistants are more like students than employees under federal labor laws.
The NLRB indicated last year that it would reconsider the question, and with the board's newly confirmed Democratic majority this week, unions may have a chance. Some universities are wary, though. Peter Weber, graduate school dean at Brown University, told lawmakers at a House hearing last year that unionizing grad students would "damage the fabric of graduate education."
One surprising area where unions have had success recently is organizing marijuana dealers in states that have legalized the drug for recreational or medical use. The United Food and Commercial Workers Union, the nation's largest union for retail workers, helped support ballot measures to legalize marijuana in Colorado and Washington last year and now counts about 3,000 members in the industry.
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