When longshoremen walked off the job in Baltimore nearly 50 years ago, their target was clear: the shipping container.

For centuries, workers went on ships and hauled out a mishmash of goods and packages, a backbreaking job that required many hands. The standardized container revolutionized the shipping industry, putting many longshoremen out of work.

Cranes, computers, deeper channels, and bigger ships meant improvements in safety, efficiency, and global trade, and unions have adapted to many of these changes over time.

But something happened during the COVID pandemic that deeply troubles the International Longshoremen’s Association. The shipping companies that employ them made an unprecedented amount of money. What if they spend it on automating American ports — and getting rid of unionized dockworkers?

The ILA went on strike Tuesday morning after their six-year contract expired, shuttering operations at ports from Texas to Maine. Yes, they want some of those record profits netted by their employers. But they also want protections from automation.

“These companies are making billions of dollars. They should take us along. We brought them to where they are,” said ILA President Harold Daggett in a video last month. “Now they want to get rid of us? That’s not fair.”

This struggle of man against machine has existed for centuries, said Bill Barry, a former union organizer and the retired director of labor studies at the Community College of Baltimore County.

“It goes back to the invention of the spinning jenny and the steam engine,” Barry said.

Every industry — from mechanized textile production to artificial intelligence in Hollywood — is grappling with how to adopt and use technology, he said.

While longshoremen marched at the entrance of the Dundalk Marine Terminal in Baltimore this week, robots hummed along the floor of a massive Amazon warehouse a few miles away, carrying stacks of goods to and from workers. Earlier this year, UPS said it intended to temporarily close a Baltimore County facility and lay off up to 540 workers there as part of a broader company strategy to increase automation through robotics and artificial intelligence.

Automation can help replace what experts call 3D work, meaning jobs that are dangerous, dirty and dull, said Tinglong Dai, a professor of operations management and business analytics at the Johns Hopkins Carey Business School.

Automating some jobs at ports could improve efficiency and make the American supply chain more flexible, Dai said. Automation is expensive and controversial, he said, but resisting it will only damage the economy in the long term.

According to Dai, automation might be especially relevant to the Port of Baltimore, which frequently leads the country in handling imported cars. It’s a point of pride for the port and its longshoremen, but Dai said self-driving cars might one day drive themselves off those ships.

That level of automation would create what economists call “structural unemployment,” said Jeremy Schwartz, who chairs the economics department at Loyola University Maryland, Sellinger School of Business and Management.

But automation isn’t all bad, Schwartz said. Sometimes it allows workers to be more efficient, without costing jobs, he said.

That’s how Eric Holt sees it. Holt is the chief commercial officer of Holt Logistics, a New Jersey-based company with nearly a century in the trucking and shipping industries. An independently managed affiliate of Holt Logistics employs about 600 to 800 ILA workers currently on strike, Holt said.

Those workers have the right to bargain, Holt said, but it’s increasingly hard to find people willing to do the job of a longshoreman.

“To me, I don’t see that as replacing jobs,” Holt said. “I see that as complementing growth and adding different types of jobs.”

Historically, though, adding machines translates to less need for dockworkers. The Port of Baltimore handles far more cargo today than it did nearly 50 years ago, when the ILA last went on strike. But Baltimore had twice as many longshoremen then, according to archival newspaper accounts.

Despite some leaps in innovation, not every job a longshoreman does is at risk of automation, according to Sal Mercogliano, a former merchant mariner and the host of a popular YouTube show called “What’s Going On With Shipping?”

There is no machine that can currently replace a lasher, Mercogliano said. Lashers are the people who clamber on top of containers and use metal rods and fittings to secure them to the ship. It’s considered one of the most dangerous jobs a longshoreman does.

Mercogliano also pointed out another reason the ILA might be resisting automation: the pensions of retirees. The union needs to sustain membership to keep contributing to those pensions, he said.

Compared to other ports internationally, American ports have been slow to adopt automation and are generally considered inefficient. In the annual ranking of more than 400 ports by the World Bank Group, American ports rarely crack the top 100. Baltimore ranked 189 last year.

The top spots are dominated by newer ports abroad that have embraced some amount of automation.

But to William Doyle, the former executive director of the Maryland Port Administration, it’s not worth spending huge sums of money to automate American ports. Every country already wants to move their cars, leaf blowers and designer handbags through American ports, he said, and a little bit of efficiency isn’t going to change that.

“We’re the world’s consumer,” said Doyle, who resigned last year and now leads a dredging contractors’ trade group. “Products are going to come here no matter what.”

Despite their 1977 strike, the longshoremen lost the battle against the shipping container, seen today as a revolutionary innovation.

Daggett took part in that strike. Now he wants to hold the line for future generations of dockworkers, fighting off technology.

“What good is it if you’re going to put people out of work? Who’s going to support their families?” Daggett said in the September video. “Machines don’t have families.”