SAN FRANCISCO — The union for thousands of West Coast dockworkers has reached a tentative agreement on a new contract, it was announced Wednesday, after more than a year of negotiations and several work disruptions that snarled shipping traffic at some of the largest ports.

The International Longshore and Warehouse Union reached the tentative deal for a new six-year contract with the Pacific Maritime Association, a trade group for cargo carriers and terminal operators. Its members include such global shipping giants as Maersk and Evergreen Marine.

The agreement will require ratification by PMA and union members and would affect 22,000 dockworkers at 29 ports from Washington state through California.

Details of the deal weren’t disclosed.

“We are pleased to have reached an agreement that recognizes the heroic efforts and personal sacrifices of the ILWU workforce in keeping our ports operating,” PMA President James McKenna and ILWU President Willie Adams said in a joint statement. “We are also pleased to turn our full attention back to the operation of the West Coast Ports.”

The dockworkers have been without a contract since July 1.

West Coast ports handle some 40% of U.S. imports and their smooth operation is so important that President Joe Biden even stepped in last year and met with both sides in Los Angeles.

The Port of Los Angeles handled 779,140 twenty-foot equivalent units last month, up 60% since February. The Port of Long Beach in May was the busiest month so far this year, signaling that volumes continue to increase.

Part of that influx are shipments tied to the upcoming holiday season that have already begun to arrive, increasing pressure to come to a new labor agreement.

“At mid-year we’re starting to see signs that cargo volume is on the upswing, with our busiest month since August of last year,” Port of Long Beach CEO Mario Cordero said this week. “We look forward to more positive signs in the months ahead.”

A lockout in 2002 and an eight-day strike in 2015 cost the U.S. economy billions of dollars and forced the administrations of then-presidents George W. Bush and Barack Obama to intervene.

The ports weren’t completely shut down this time but several short-term worker shortages in recent weeks disrupted or even closed some terminals in California and Washington.

“Although there have been a couple terminal closures at Los Angeles/Long Beach around holidays, disruptions don’t appear to be having a meaningful impact so far. The situation, however, at the smaller Port of Seattle has been more concerning, resulting in terminal closures and more meaningful delays in recent days,” Christian Wetherbee of Citi Investment Research said in a note to clients.

After the COVID-19 pandemic began to take hold in 2020, cargo traffic to ports slumped drastically. But then it recovered. Soaring demand led to traffic jams at the twin ports of Los Angeles and Long Beach, the nation’s busiest port complex.

The union sought higher wages, arguing they deserved a greater share of record profits made by shippers and terminal operators during the pandemic.

“ILWU workers risked and lost their lives during the pandemic to ensure grocery store shelves were stocked, PPE (health safety gear) was made available, essential medical supplies were reaching our hospitals, and record volumes of consumer goods continued to reach the door steps of American consumers,” argued an ILWU statement on June 2.

Biden extended congratulations to workers, cargo carriers and terminal operators Thursday afternoon.

“I want to thank both sides for staying at the table and reaching a deal,” Biden said. “And special thanks to the longshore workers who worked historically through this pandemic, and really heroically as well, and they’re finally going to get the pay and benefits and equality they deserve.”

Acting U.S. Secretary of Labor Julie Su was sent to assist in the negotiations and the White House hopes her part in the sealing the deal helps to get her stalled nomination for the permanent job moving again.

“Special thanks to acting Secretary of Labor Julie Su who used her deep experience and judgement to keep parties talking throughout the negotiations,” Biden said. “And this is going to have a real positive impact on trade. She’s shown she’s a true leader and I think she should be confirmed.”

The tentative agreement was praised by Los Angeles Mayor Karen Bass, who said port work generates 1 in 15 jobs in the city.

“This is a win for the working people of our city,” she said.