If you felt a rush of air Wednesday night, that was a sigh of relief reverberating along the East Coast.

After months of anxiety that mid-January could bring a second longshoremen strike, a dockworkers union and the operators of port terminals reached an agreement that would avert a work stoppage. The International Longshoremen’s Association, the union representing East and Gulf Coast workers, and the United States Maritime Alliance, a coalition of shipping lines and port operators, tentatively agreed on six-year contract, the two groups said in a news release Wednesday.

At the crux of protracted negotiations had been automated technology, which the union worried would take away jobs.

“This agreement protects current ILA jobs and establishes a framework for implementing technologies that will create more jobs while modernizing East and Gulf coast ports — making them safer and more efficient, and creating the capacity they need to keep our supply chains strong,” the two sides said in a joint statement.

The East Coast, including the Port of Baltimore, saw a three-day strike in October that was suspended until mid-January. In recent weeks, a continuation of that work stoppage seemed likely.

In a Christmas Day letter, Harold Daggett, the president of the ILA, said that although the union wanted to avoid another strike, “our resolve may be tested again in mid-January.”

Shipping lines took note, too. Maersk, a Danish shipper, warned customers Dec. 30 about the possibility of a work stoppage affecting the supply chain. It “strongly” encouraged customers to pick up laden containers and return empty ones on the East Coast before Jan. 15.

Consequences of the strike would have slowed the ever-beating ports, which are integral to the American economy. Daggett credited a December meeting with President-elect Donald Trump as “the chief reason the ILA was able to win protections against automation.”

In a statement, President Joe Biden applauded the dockworkers’ union for “delivering a strong contract.”

“Their members kept our ports open during the pandemic as we worked together to unsnarl global supply chains. Thank you to the carriers and port operators who play an essential role in our nation’s economy,” Biden said.

Effects would have been particularly felt in Baltimore, the nation’s busiest car port, and which suffered last year after the Francis Scott Key Bridge collapse on March 26 blocked the shipping channel for several weeks. Avoiding a work stoppage is “tremendous news for all of us in the maritime industry and a great start to the new year,” the Port of Baltimore posted on a social media account.

Ports aren’t out of the woods, though.

If Trump installs wide-reaching tariffs on some of America’s top trade partners, as he’s threatened, it would likely slow shipments in and out of the Port of Baltimore. For example, Trump has warned against a 25% tariff on Mexico, which ships more cars than any other country to Baltimore.