“You don’t have to pay pensions to robots,” Brian Jones, a foreman at the Port of Philadelphia, told the New York Times in September. Dockworkers on the West Coast struck a deal with the Maritime Alliance last year. They secured a pay raise without having to strike but did not stop the rollout of automation.

Dockworkers at ports from Maine to Texas began walking picket lines early Tuesday in a strike over wages and automation that could reignite inflation and cause shortages of goods if it goes on more than a few weeks.