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.
What to Know about Michigan's new law
LANSING, Mich. (AP) -- Here are five things to know about right-to-work legislation approved by the Michigan Legislature and signed into law by Gov. Rick Snyder:
THE NAME IS MISLEADING
It isn't about a right to work but rather a right for workers to choose whether they want to join a union or pay fees that amount to union dues. The legislation prohibits what are known as "closed shops," where workers have no choice but to join a union or pay those fees.
IT MOVED SWIFTLY
The GOP majority used its superior numbers and backing from Gov. Rick Snyder to ramrod legislation through the House and Senate last week. They brushed aside denunciations and challenges by helpless Democrats and cries of outrage from thousands of union activists who swarmed the state Capitol hallways and grounds. Snyder signed the bills into law Tuesday, hours after the final House votes.
BUT DIDN'T OVER EASILY
Supporters, including Republican leaders in the Legislature and the Michigan Chamber of Commerce, insist it's about freedom of association for workers and a better business climate. Critics, including Democrats and Michigan's sizable labor contingent, contend the real intent is to bleed unions of money and bargaining power and allow nonunion workers to get the perks without paying for it. Thousands protested at the Michigan Capitol, but even they acknowledged before the final votes that it would inevitably become law.
IT'S NOT THE FIRST
Michigan becomes the 24th state with such laws. Victory in the Great Lakes State gives the right-to-work movement its strongest foothold yet in the Rust Belt region, where organized labor already has suffered several body blows. Republicans in Indiana and Wisconsin recently pushed through legislation curbing union rights, sparking long, massive protests.
RUST BELT RERUN?
Law enforcement officials vowed Michigan won't become "another Wisconsin," where demonstrators occupied the state Capitol around the clock for nearly three weeks. They took steps to prevent that.
Last Thursday, eight people were arrested - and a few of them pepper-sprayed - after authorities say they disobeyed orders and tried to rush past two state troopers and into the Senate chamber. Out of concerns for the safety of people and the historic building, authorities said, they temporarily closed the building and kept hundreds outside. A judge later ordered it reopened.
Police say they are mindful of the need to keep "the people's house" open if at all possible but are keeping a close eye on areas that are becoming overcrowded and would close them off if necessary. They also significantly stepped up police presence to correspond with the number of demonstrators coming from across the state and beyond.
They say they used pepper spray again Tuesday to subdue a protester outside the Capitol who had his hands on a female trooper being pulled into a crowd. Police also arrested two people after they tried to get into a state office building where the governor has an office.
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.
The latest from Michigan:
LANSING, Mich. (AP) -- In a dizzyingly short time span, Republicans have converted Michigan from a seemingly impregnable fortress of organized labor into a right-to-work state, leaving outgunned Democrats and union activists with little recourse but to shake their fists and seek retribution at the ballot box.
The state House swiftly approved two bills reducing unions' strength Tuesday, one dealing with private-sector workers and the other with public employees, as thousands of furious protesters at the state Capitol roared in vain. Republican Gov. Rick Snyder signed the measures into law within hours, calling them "pro-worker and pro-Michigan."
"Workers deserve the right to decide for themselves whether union membership benefits them," Snyder said. "Introducing freedom-to-work in Michigan will contribute to our state's economic comeback while preserving the roles of unions and collective bargaining."
House Speaker Jase Bolger exulted after the vote that Michigan's future "has never been brighter," while Democrats and union activists said workers had been doomed to ever-lower living standards. Lacking enough votes to block the measures or force a statewide referendum, opponents set their sights on the 2014 election.
"Passing these bills is an act of war on Michigan's middle class, and I hope the governor and the Republican legislators are ready for the fight that is about to ensue," said Gretchen Whitmer, the Senate Democratic leader.
As 1 of 24 states with right-to-work laws, Michigan will prohibit requiring nonunion employees to pay unions for negotiating contracts, representing them in grievances and other services. Supporters say the laws give workers freedom of association and promote job creation, while critics insist the real intent is to drain unions of funds need to bargain effectively.
Labor has suffered a series of setbacks in Rust Belt states since the 2010 election propelled tea party conservatives to power across much of the region. Even so, the ruthless efficiency with which Republicans prevailed on right-to-work was breathtaking in Michigan, birthplace of the United Auto Workers, where unions have long been political titans.
The seeds were planted two years ago with the election of Snyder, a former venture capitalist and CEO who pledged to make the state more business-friendly, and GOP supermajorities in the House and Senate. They have chipped away repeatedly at union power, even as Snyder insisted the big prize - right-to-work - was "not on my agenda."
Fearing the governor wouldn't be able to restrain his allies in the Legislature, labor waged a pre-emptive strike with a ballot initiative known as Proposal 2 that would have made right-to-work laws unconstitutional. It was soundly defeated in last month's election, and Snyder said Tuesday the unions had miscalculated by bringing the issue to center stage.
"I don't believe we would be standing here in this time frame if it hadn't been for Proposal 2," the governor said at a news conference after signing the bills. "After the election, there was an extreme escalation on right-to-work that was very divisive."
After days of private talks with legislative and union leaders, Snyder threw his support behind the measures last Thursday. Within hours, Senate Republicans had introduced and approved them without the usual committee hearings. After a mandatory five-day waiting period, the House did likewise Tuesday.
It happened so quickly that opponents had little time to generate the massive resistance put forward in Indiana, where right-to-work was approved earlier this year, and Wisconsin during consideration of a 2011 law curtailing collective bargaining rights for most state employees. Those measures provoked weeks of intense debate, with Democrats boycotting sessions to delay action and tens of thousands of activists occupying statehouses.
Still, Michigan unions mustered thousands of protesters who massed in the Capitol's hallways, rotunda and front lawn. Crowds formed before dawn on a chilly morning. Four oversized, inflatable toy rats bearing the names of Snyder and GOP legislative leaders were on display.
"They're selfish. They're greedy. They're Republican," said Susan Laurin, 60, of Saginaw, a secretary with the state Department of Transportation, wearing a hard hat like many fellow demonstrators.
Seventh-grade teacher Jack Johnson, of East Lansing, said the GOP's goal was obvious: "You take away money from the unions and they can't support the Democratic candidates, and the Republicans take over."
"No justice, no peace!" protesters chanted, the chorus reaching a deafening din as the House prepared to vote. "Shame on you!" they shouted from the House gallery as the results were announced.
Republicans insisted the bills were given adequate consideration, as the issue had been debated across the state for years. Snyder said he saw no reason to delay signing the measures, especially with opponents still hoping to dissuade him.
"They can finish up, and they can go home because they know ... making more comments on that is not going to change the outcome," he said. "I view this as simply trying to get this issue behind us."
Don't count on it, state Democratic Chairman Mark Brewer retorted.
"If Gov. Snyder thinks that Michigan citizens will go home and forget about what happened in Lansing today, he is sorely mistaken," state Democratic Chairman Mark Brewer said. "Snyder has set the tone for the next two years, and this fight is not over."
Snyder said he expects the law to be challenged in court but believes it will stand. Opponents also said they might seek recalls of some legislators.
Meanwhile, unions must adapt to a new reality.
The laws take effect 90 days after the Legislature adjourns. Even then, workers bound by existing contracts won't be able to stop paying union fees until those deals expire. But activists fear some will opt out at first opportunity.
"A lot of people like to freeload," said Sharon McMullen, an employee of the state Department of Licensing and Regulatory Affairs.