Workers who load and unload shipping containers from cargo ships are at an impasse in labor contract negotiations.

Dockworkers at 15 ports from Texas to Maine were all but certain to go out on strike early Tuesday, a move that could raise prices on goods and cause shortages and price increases as the holiday shopping season approaches.

Port workers 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.