The United States Maritime Alliance said on Wednesday it reached a tentative agreement on a new six-year master contract with the International Longshoremen’s Association.

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

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.