A potential strike at a US port could delay the transport of goods for months, according to shipping experts

A potential attack on U.S. seaports on the East Coast and the Gulf of Mexico could delay cargo shipping there for weeks or even months, shipping experts said Wednesday.

Retailers like Walmart and other importers have been rushing to import products before the Sept. 30 expiration of the union contract covering about 45,000 longshore workers at three dozen seaports from Texas to Maine.

Their goal? To unload the cargo in the United States before October 1, when the International Longshoremen's Association, which represents the workers, has promised to strike if a new contract is not signed.

Analysts at Sea-Intelligence, a Copenhagen-based maritime advisory firm, estimated it could take four to six days to clear the backlog caused by a one-day strike.

“This means that a one-week strike in early October would not end until mid-November,” Sea-Intelligence chief executive Alan Murphy said in a statement.

A two-week strike could mean ports would not return to normal operations until 2025, Murphy said.

These findings echo a warning from A.P. Moller-Maersk, one of the largest shipping providers. Maersk said a one-week shutdown could require up to six weeks of recovery time, “with significant backlogs and delays worsening with each passing day.”

The early shipping strategy has come at a high cost to shippers. The uncontracted spot market price to ship a 40-foot container to the U.S. East Coast from the Far East topped $10,000 in early July, up from $2,100 in early April, said Peter Sand, chief analyst at pricing platform Xeneta.

“The risk of strikes in ports was something that had to be addressed by taking early action,” Sand said.

That window is closing as the deadline for a new deal approaches. That’s because ship diversions due to attacks by Yemen’s Houthis in the Red Sea mean it can take 45 days or more to transport goods to East Coast and Gulf ports from factories in Asia.

“Shipping cargoes next week… will really be too late as they could be stuck in the water” if ports are hit by widespread strikes, Sand said.