Here is a look at the landscape in some Rust Belt states that have pushed for right-to-work plans in recent years -- some successfully, others not:
Illinois has not seen a serious right-to-work movement largely because of a near Democratic lock on the General Assembly in the past 30 years. During much of that time, the state had Republican governors, but they tended to be moderates who dealt with labor amicably. And when the GOP held the state Senate during the 1990s, there were many moderate Republicans from suburban Chicago who balanced out more conservative lawmakers from central and southern Illinois.
The Republican-controlled Legislature in Indiana approved right-to-work earlier this year. House Democrats walked out in 2011 for five weeks to block the measure by denying the GOP majority the numbers needed to conduct business. The state's quasi-public economic development corporation says a handful of companies have expanded operations in part because of the law.
The labor stronghold of Michigan became the 24th state to enact right-to-work on Tuesday when the House approved the final version of the legislation and Republican Gov. Rick Snyder signed it hours later. Snyder had previously maintained that right-to-work wasn't a priority for him, but the plan sailed through the GOP-controlled Legislature after he announced his new position last week. While labor unions said the move would be disastrous for worker rights and benefits, Snyder insisted the plan is actually "pro-worker."
Ohio voters in 2011 overwhelmingly rejected a sweeping law that placed restrictions on public employee unions. Republican Gov. John Kasich says making Ohio a right-to-work state is not among his priorities and that he sees other ways to keep the state competitive. However, a group called Ohioans for Workplace Freedom has been circulating petitions for a ballot measure that would keep workers covered by labor contracts from having to join a union or pay dues.
Pennsylvania labor unions have been largely successful in pushing back against efforts by first-term Republican Gov. Tom Corbett to dramatically scale back their gains. But Corbett says the state apparently lacks the political will to enact right to work. However, his spokesman says the governor would support such a bill if it reached his desk.
Wisconsin's Republican-controlled Legislature in 2011 voted to pass Gov. Scott Walker's proposal that effectively ended collective bargaining for most public workers and forced them to pay more for health insurance and pension benefits. Walker argued it was a cost-saving move, but unions said it was designed to cripple their political power. Walker did not propose right-to-work legislation and has said that is not a priority, but he's stopped short of saying he would veto such a measure.
Associated Press writers Marc Levy in Harrisburg, Pa., John O'Connor in Springfield, Ill., Ann Sanner in Columbus, Ohio, Scott Bauer in Madison, Wis., and Tom LoBianco in Indianapolis contributed to this report.