A massive strike across the U.S. East and Gulf Coast ports has been averted after a dockworker union and an alliance of companies, terminal operators, and port associations, negotiated a new labor contract.

The union representing 45,000 dock workers on the U.S. East and Gulf Coasts and their employers on Wednesday said they reached a tentative deal on a new six-year contract, averting further strikes that could have snarled supply chains and taken a toll on the U.

Automation was at the center of a long-running labor dispute that threatened to close East and Gulf Coast ports.