The union representing U.S. dockworkers has signaled that 45,000 members will walk off the job at midnight, kicking off a massive strike likely to shut down ports across the East and Gulf coasts.

Dockworkers at ports from Maine to Texas have started walking picket lines in a strike over wages that could cause real problems if it goes on for more than a few weeks.

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.