The rally, which began with a nearly 1.5-mile march along Route 21, is one of the first outside the states where lawmakers are already battling over collective bargaining rights.

In Wisconsin, Republican Gov. Scott Walker signed legislation last month stripping nearly all collective bargaining rights from most state employees.

On Wednesday, Ohio lawmakers passed a bill that was in some ways tougher than Wisconsin's and sent it to the governor, extending restrictions to police officers and firefighters, as well as to teachers, nurses and a host of other government personnel. Republican Gov. John Kasich signed it into law Thursday.

It allows unions to negotiate wages but not health care, sick time or pension benefits. It gets rid of automatic pay increases and replaces them with merit raises or performance pay. Workers would also be banned from striking.

Some at Friday's rally wore round decals with a red slash across the number 5, meaning Ohio Senate Bill 5.

Tim Burga, president of the Ohio AFL-CIO and a third-generation steelworker, warned the miners that politicians and corporations are coming after everything unions hold dear, from collective bargaining and overtime pay to prevailing wages and union shops.

"We have an opportunity in Ohio to create a new movement," he said. "Help us in Ohio. We're going to overturn Senate Bill 5."

More than 3,500 members of the United Mine Workers of America, their families and other supporters from Pennsylvania, Maryland, Ohio, Virginia and West Virginia attended the solidarity day, chanting "This is what democracy looks like!"

Camouflage signs were lettered in yellow with "We Are One … This Fight Is Just Starting," and many in the crowd wore red buttons with a blue clenched fist that said "Stand with Wisconsin."

Efforts to limit union powers are also under way in Florida, Iowa, Tennessee, Indiana and more states with Republicans in charge.

UMWA President Cecil Roberts warned his rank and file that it's not just public employees they want to rein in.

"They are talking about you," he shouted, as the crowd shivered and cheered. "I got news for you: Today it's the public employees, tomorrow it's the steelworkers. Tomorrow it's the autoworkers. Tomorrow it's the coal miners. Now is the time to stand up and fight back!"

Roberts invoked the words of the Rev. Martin Luther King Jr. in warning of growing anger around the country,

"He would say, 'How long before freedom comes? … How long? Not long!'" Roberts said. "How long before working class people stand up to these rich millionaires? How long? Not long!"

The UMW is about to begin negotiations on a new nationwide coal contract to replace the one expiring Dec. 31, and it's publicly pressing Virginia-based Alpha Natural Resources to open two new coal mines in western Pennsylvania and make them union operations.

At the height of labor's influence in the 1950s, union membership peaked at about one of every three workers, but unions have since fought steady erosion. The Bureau of Labor Statistics says union membership last year fell to just less than 12 percent of all workers, and just less than 7 percent in the private sector.

In 2009, for the first time, more union members were working for federal, state and local governments than in the private sector.

Labor's power today may be diminished, but it's far from done, said former AFSCME secretary-treasurer Bill Lucy, who called the current conflict "a battle between Wall Street greedy and Main Street needy."

"If you do not fight back, you are certain to lose," he told the crowd. "We will fight until hell freezes over — and then we'll skate across the ice and bring you one more lick."

United Steelworkers President Leo Gerard said younger generations need to be reminded that the benefits they have today weren't gifts from generous employers.

"We only got what we were strong enough to take," he said, "and we're going to take it back."

Some in the crowd believed it.

"The pendulum is swinging the other way," said Regis Bozek, 57, of Masontown, Pa., who has worked at Alpha's Cumberland mine for 33 years. "What people don't realize is when we're gone, the good wages are gone. My kids will never live as good as our generation did."

Margaret Starkey, 66, of Madison, W.Va., joined more than 100 people from Boone County who traveled from the southern coalfields to remind young people what previous generations have brought them — fair wages, a 40-hour workweek, paid time off and more.

"You'd better be standing up for the union," she said. "Because when they get rid of the unions, you're going to be working for nothing."