Every year the U.S. Bureau of Labor Statistics takes the temperature of labor unions with two distinct measures: the number of people in unions and the number of major strikes and lockouts involving 1,000 or more workers.
That first measure has been declining since the government started to keep track -- which was only relatively recently in 2000, when 13.4 percent of all workers were union members. Last year that was down to 11.3 percent.
The second benchmark, the number of strikes involving 1,000 or more workers, has been a subject of study by the BLS since just after World War II.
Back in the late 1940s and early 1950s, every year the number of large strikes was in the hundreds, and generally those work stoppages combined idled more than a million and a half workers a year.
The record for strikes and lockouts was set in 1952, when 470 separate strikes affected a total of 2.7 million workers, causing nearly 49 million days of work lost.
The country hasn't seen a rash of major strikes in more than 30 years now. Last year, 19 work stoppages put 148,000 workers on the street for a combined 1.1 million days.
While in the past work stoppages were known to last for weeks and months, 13 of the 19 strikes or lockouts in 2012 lasted less than a week, with seven of them just a day or two.
One of the more well-known lockouts, at Hostess Brands, ran less than three weeks but ended with the closure of the company.
Charles McCollester, a retired professor of industrial history and labor relations at Indiana University of Pennsylvania, said it is not just that labor unions are weaker than they used to be, but so, too, are the companies.
"It's hard to have a strike," he said. "You have to have a healthy company, a strong union and community support."
In the middle of the 20th century, there were factors that made unions much stronger, including limited competition from overseas and a stronger manufacturing sector.
Mr. McCollester said coal miners and factory workers created strong unions because they were so dependent on each other for their collective safety that they stayed bonded for collective bargaining.
The longest strike in Pennsylvania history ended in defeat for the United Mine Workers. Workers were out from 1988 to 1992 at the Canterbury Coal mine in Apollo. The mine closed a few years later.
Mr. McCollester pointed out that there was no victory for either side after the long strike.
He said there are a lot of reasons not to strike anymore.
"It's a tough world out there. And you never know what's going to happen once you walk out the door," he said.
Tony Montana, a spokesman for the United Steelworkers, said unions have also become smarter about negotiations so that strikes, which were always the last resort, are now a rarity.
"Both unions and employers have been more responsible and smarter and more open to negotiating through our differences at the table," Mr. Montana said.
An example of that, he said, was the agreement reached in October between the USW and ArcelorMittal, the world's largest steel manufacturer.
The company had demanded 36 percent cuts in wages and benefits, but agreed to increases of 2 percent effective in September 2013 and another 2.5 percent increase in 2015 with agreements in the works regarding efficiency and productivity.
That contract was adopted by workers with a huge majority without any work stoppage at all.
Ann Belser: email@example.com or 412-263-1699.