(NewsNation) — Dockworkers at ports from Maine to Texas are on strike, a standoff that may affect prices on items including food and cars.

The contract between the ports and about 45,000 members of the International Longshoremen’s Association expired at midnight, and even though progress was reported in talks Monday, the workers went on strike. The strike affecting 36 ports is the first by the union since 1977.

Workers began picketing at the Port of Philadelphia shortly after midnight, walking in a circle at a rail crossing outside the port and chanting “No work without a fair contract.”

The union had message boards on the side of a truck reading: “Automation Hurts Families: ILA Stands For Job Protection.”

The U.S. Maritime Alliance, which represents the ports, said Monday evening that both sides had moved off of their previous wage offers, but when picket lines went up just after midnight, it was apparent that no deal had been reached.

Why are Longshoremen going on strike?

The International Longshoremen’s Association had threatened to strike at 12:01 a.m. Tuesday, a move that could choke off activity at ports that handle about half the ship cargo coming in and going out of the U.S.

A message was left Monday evening seeking comment from the union.

“We are hopeful that this could allow us to fully resume collective bargaining around the other outstanding issues in an effort to reach an agreement,” the alliance statement said.

The Alliance said its latest offer would increases wages by nearly 50% over the six-year contract, and triple employer contributions to retirement plans. The offer also would strengthen health care options and keep current language that limits automation.

The union has demanded 77% pay raises over six years to help deal with inflation. Many of the ILA workers can make more than $200,000 per year, but the union says they must work large amounts of overtime to reach that figure.

The two sides had not held formal negotiations since June, and a strike appeared imminent. In a statement Monday morning, the union said the ports had refused its demands for a fair contract and the alliance seemed intent on a strike. The alliance has said it was willing to bargain.

How a Longshoremen strike could affect the economy

A work stoppage would significantly snarl the nation’s supply chain, potentially leading to higher prices and delays in goods reaching households and businesses if it drags on for weeks.

If drawn out, the strike would force businesses to pay shippers for delays and cause some goods to arrive late for peak holiday shopping season — potentially impacting delivery of anything from toys or artificial Christmas trees, to cars, coffee and fruit.

A strike could have an almost immediate impact on supplies of perishable imports such as bananas, for example. The ports that could be affected by the strike handle 3.8 million metric tons of bananas each year, or 75% of the nation’s supply, according to the American Farm Bureau Federation.

Americans could also face higher prices as retailers feel the supply squeeze.

“If the strikes go ahead, they will cause enormous delays across the supply chain, a ripple effect which will no doubt roll into 2025 and cause chaos across the industry,” noted Jay Dhokia, founder of supply chain management and logistics firm Pro3PL.

Dhokia added that East Coast ports aren’t the only ones at risk for disruption, as concern leading up to the strike has already diverted many shipments out West, adding to route congestion and more pressure on demand. Impacts will also be felt internationally — particularly in places such as the United Kingdom, he said, where the U.S. is its largest trading partner.

In addition to higher wages, ILA members want a total ban on the automation of cranes, gates and container-moving trucks used in the loading or unloading of freight.

A strike by the ILA workers — set to impact ports from Maine to Texas — would be the first by the union since 1977. West Coast dockworkers belong to a different union and aren’t involved in the strike.

If a strike were deemed a danger to U.S. economic health, President Joe Biden could, under the 1947 Taft-Hartley Act, seek a court order for an 80-day cooling-off period. That would suspend the strike.

What role is Biden playing?

All eyes were on what, if any, action the administration might take — particularly just weeks ahead of a tight presidential election. But Biden has signaled that he will not exercise this power.

During an exchange with reporters Sunday, Biden said “no” when asked if he planned to intervene in the potential work stoppage.

“Because it’s collective bargaining, I don’t believe in Taft-Hartley,” he said.

NewsNation political contributor Scott Bolden said Biden was likely “keeping his fingers crossed.”

“I think behind the scenes, Biden is pushing hard on both sides and basically telling the union: ‘Don’t make me do this,'” Bolden said during an appearance on NewsNation’s “The Hill.“

A White House official said that at Biden’s direction, the administration has been in regular communication with the ILA and the alliance to keep the negotiations moving forward. The president directed Chief of Staff Jeff Zients and National Economic Council Director Lael Brainard to convene the alliance’s board members Monday afternoon and urge them to resolve the dispute fairly and quickly — in a way that accounts for the success of shipping companies in recent years and contributions of union workers.