But no model of labor relations can last forever. This one worked as long as the United States remained largely a closed economy. Unions roughly ensured that working standards improved uniformly across many industrial sectors. If they negotiated higher wages or better working conditions at one airline or car company, others quickly followed — even nonunion shops, which hoped to appease workers and prevent them from voting for a union.

Yet economic changes upended the pattern again. The new jobs created around the revolution in information technology of the late 20th century did not fit the mold of the corporations of old. New companies relied more on independent contractors and freelance work. The lifelong relationship established between industrial companies and their workers gave way to looser, shorter dalliances.

Perhaps most important, globalization exposed America’s industrial-era titans to more intense competition. The emergence of powerful rivals overseas, where labor was cheap and unions scarce, made it more difficult for companies to improve wages and working conditions without becoming less competitive. And corporations, especially new high-tech companies that arose in southern states where labor law made it tougher to organize, turned against unions as albatrosses around their necks.

Unsurprisingly, a majority of unionized workers today are employed by the government, the last sector of the economy that is largely protected from foreign competition. “We are forced to conclude that a resurgence of labor unions in the private sector in the foreseeable future is unlikely,” wrote the labor market scholars Henry S. Farber and Bruce Western of Princeton University a decade ago, echoing Mr. Barnett’s thoughts 70 years before. And things have only deteriorated for the unions since then.

But if the prospects look grim for the unions of America’s industrial era, the precedent of the 1930s — when workers organized in droves — offers perhaps a hint of a path for organized labor as the economy works its way forward from the Great Recession, a role that perhaps better fits the nation’s corporate makeup.

The future labor movement may have to give up organizing work site by work site. Its biggest political fight in the last few years — pushing a law to make it easier to organize a workplace — may be irrelevant. And fighting to create new barriers to foreign competition is probably a lost cause. Instead of negotiating for their members only, unions might do better pulling for better wages and conditions for all workers.

Some scholars, like the economist Richard B. Freeman of the National Bureau of Economic Research, suggest the labor movement could take a page from the AARP’s playbook and become a lobbying group. German-like worker councils could discuss workplace issues with management, without negotiating over pay.