LOS ANGELES — The nation’s busiest ports, the Ports of Los Angeles and Long Beach, have been hit with a labor strike at the height of holiday shopping season, causing a major work stoppage at the country’s largest commercial shipping center.

This story first appeared in the November 29, 2012 issue of WWD. Subscribe Today.

The strike began on Tuesday, when activity came to a halt at the APM Terminal, one of eight operating container terminals at the Port of Los Angeles, due to a walkout by 67 workers from the International Longshore and Warehouse Union Local 63’s Office Clerical Unit. By Wednesday, the rest of the 800-member clerical unit followed suit, defying an order from a labor arbitrator to return to work Tuesday night after the picket lines were declared invalid. The work stoppage has since spread to seven terminals at the Port of Los Angeles and three of the six container terminals at neighboring Port of Long Beach.

“A work stoppage at America’s two busiest ports just as the holiday shopping season begins is a recipe for disaster,” said Retail Industry Leaders Association president Sandy Kennedy. “If the strike isn’t resolved quickly, the effects on retailers, their customers and the economy will be enormous. We urge the parties to quickly resolve the dispute and get back to work in order to avoid the substantial economic damage a prolonged work stoppage would surely cause.”

The ILWU is worried that shipping companies, represented by the Harbor Employers Association, are trying to outsource clerical jobs to nonunion labor, a dispute that has been simmering since negotiations started when the old agreement expired on June 30, 2010.