U.S. ports along the East and Gulf Coasts are extending delivery hours for importers as they rush to clear cargo ahead of a potential strike by dockworkers on Oct. 1.

Ports from New York to Virginia are also working on contingency plans to avoid disruptions after some 45,000 dockworkers aligned to the International Longshoremen's Association threatened a walkout if they did not have a new labor contract in place when the current deal expires on Sept. 30.

A potential closure of 36 ports along the East and Gulf Coasts, including five of the 10 busiest ports in North America, is expected to choke the already strained supply chain and make it a logistical nightmare for companies to divert their freight to other areas.

Maher and Maersk's APM, which are members of the employer negotiating group (USMX), said they were keeping their terminals at the Port of New York and New Jersey open for two additional hours to clear cargo.

The Port of New York and New Jersey is the busiest on the East and Gulf Coasts. It handles on average 15,000-16,000 TEUs (twenty-foot equivalent units) daily, or about $240 billion worth of goods moved each year.

"We are coordinating with partners across the supply chain to prepare for any potential impacts," Port Authority of New York and New Jersey (PANYNJ) spokesperson Steve Burns said.

As of Saturday, there were 42 container ships scheduled to arrive at the Port of New York and New Jersey, one of the biggest ports involved in the labor dispute, according to S&P Global's maritime tracking service Sea-web. Thirteen ships are scheduled to arrive after Sept. 30.

The Garden City Terminal at the Port of Savannah and the Norfolk International Terminal at the Port of Virginia have also extended their gate hours for the weekend before Sept. 30 to clear cargo.