When Michigan's right-to-work law takes effect Thursday it will signal the latest sign of turmoil in the union movement that has seen nationwide membership shrink to its lowest levels since at least the 1930s.
More losses could come under the law which stops mandatory employee payments to unions representing them in collective bargaining agreements.
The law was signed last December by Gov. Rick Snyder.
United Auto Workers Local 174 member John Zimmick in Detroit says Michigan's law will weaken, but not "kill" the union.
Nationally, unions have 14.4 million members and can be potent political forces at the ballot box. But they have had to deal with protests in recent years over the passage of right-to-work laws in Michigan and Indiana, and clashes over collective bargaining in Wisconsin and Ohio.