Michigan has become the 24th right-to-work state.
But it will take months or years to know the true effect in a state with the nation's seventh-highest percentage of unionized workers.
The historic law applies to labor contracts that are extended or renewed starting Thursday, so many employees will not be affected until their existing collective bargaining agreements end.
Ford Motor Co. line worker Terry Bowman is leaning toward ending his membership in the United Auto Workers when the contract ends in 2015. He says the union has become too political instead of focusing on workers at his plant in Ypsilanti.
He says there are many more blue-collar people like him, but they are scared to publicly support right-to-work.
Staunch union advocates say the law will depress wages and benefits.