Dockworkers and their employers have agreed to extend contract negotiations for an additional 30 days, averting a strike that would have shut down seaports along the East Coast and Gulf of Mexico.

The International Longshoremen’s Association and the U.S. Maritime Alliance will continue negotiations for another 30 days, according to the Federal Mediation and Conciliation Service, which is working with the two groups. A strike would have closed ports from Maine to Texas that handle 45 percent of U.S. commerce.