Unions, of course, have been in retreat for years. But Ms. Pope and several other women, notably Rose Ann DeMoro, of National Nurses United, and Mary Kay Henry, of the Service Employees International Union, are pushing back. Their ascendance has rekindled hope that organized labor maybe, just maybe, could stage a comeback. They have also helped inspire the likes of Occupy Wall Street.

“Some of these women might even make unions relevant to the average American again,” said Steve Early, a labor journalist, union organizer and author of “The Civil Wars in U.S. Labor.”

That, anyway, is labor’s hope. All three women are pushing the old boundaries, and some are engaging traditional foes like anti-union managers and Republicans in Washington and beyond.

From Big Rig to Bargaining

Ms. Pope is an unlikely firebrand. Her father was an investment banker, and she grew up in comfortable surroundings in a Boston suburb. But then she dropped out of Hampshire College and ended up working for minimum wage as an attendant at a psychiatric hospital. When co-workers groused about wages, she organized a strike — and won.

“I saw how empowered people felt when they had control over their lives,” she recalled.

Ms. Pope later found a better-paying job at a warehouse in Cleveland, as a member of the Teamsters. In 1979, when Teamster steel haulers in Canton, Ohio, went on strike, she helped expand that action throughout the Midwest. Before long, she was driving an 18-wheeler, hauling steel from Cleveland to Baltimore. After the birth of her first child, however, she traded her rig for the bargaining table, and began negotiating local contracts. When Ron Carey, a parcel truck driver from Queens, ran on an anticorruption platform and captured the presidency of the Teamsters, a union that had been long notorious for Mafia connections, Ms. Pope became an international representative for the union’s warehouse unit. By then, she had settled in Montclair, N.J.