As an economist, Mark Price can see the trends as easily as he can see lines on a graph.

From 1947 until 1973, real incomes for families doubled across the economic spectrum. It was a time, he said, of "broadly shared prosperity" and high union membership.

In 1973, union membership was just below a third of all workers, but since then membership has dropped to about 16 percent. Since then, the bulk of the prosperity has shifted to the upper rungs of the economic ladder, with the middle class typically losing ground.

So, while productivity has continued to see gains, compensation for all but the top percentage of earners has remained flat, and workers are taking home $2,000 less per year than they did in 2000, in inflation-adjusted dollars.

Mr. Price was speaking to a group of unionists gathered at the United Steelworkers building, Downtown, as part of the labor movement's renewed push for the Employee Free Choice Act, which would, in part, make it easier to form a union.

"Union membership raises wages by 10 percent," Mr. Price said.

Jack Shea, the president of the Allegheny County Labor Council, said that, according to a survey by a labor organization, "60 million [Americans] said 'I would join a union tomorrow if I had the opportunity.' "

"Once you start building the unions, you're building the middle class," Mr. Shea said. "The people who are against the Employee Free Choice Act are the same people who got us into this mess to begin with."

The discussion yesterday coincided with the release of a report by The Center for American Progress Action Fund which pointed out that union members are 28.2 percent more likely to receive health insurance from their employers and 53.9 percent more likely to have pension plans from their employers.

In a national report, the center noted that if union membership were to return to 1983 levels, those newly unionized workers would earn a total of about $49 billion more per year. In Pennsylvania, that would translate into a 5 percent increase in union membership, and an increase of $852 million in wages for those workers.

Keli Vereb, a member of Lincoln Borough Council, also is a member of the United Steelworkers Local 1408 and schedules when work will be done for U.S. Steel.

She was a single mother, living with her parents, in the early 1990s when she worked during the day and went to school at night. After her college graduation, she started out in a low-paying job with no benefits. Then she landed at U.S. Steel. As a union member, her paycheck more than doubled, she and her daughter received health insurance, and she entered a company-sponsored pension plan.

Now, as a borough council member, she has worked to make sure her local police remain in a union, and the borough has adopted a "Buy American" policy.

Geneva Turner has her own plan to campaign for the Employee Free Choice Act. Ms. Turner is the secretary-treasurer of United Food and Commercial Workers Local 325, which represents workers at the former H.J. Heinz plant, now owned by Bay Valley Foods.

Ms. Turner will carry pamphlets to Wal-Mart urging workers there to support the Employee Free Choice Act. She said she would hide pamphlets in a cart and hand them to employees. Wal-Mart has taken a strong stance against unionization.

Mr. Price said it was easy to see the effect of a decrease in union membership in the country: "Productivity is continuing to rise, but it's not being realized in wages."