THE leading US automobile workers’ union has started a strike against all three Detroit carmakers for the first time in its 88-year history.

Members of the United Auto Workers began picketing at midnight at three locations — a General Motors plant in Missouri, a Stellantis plant in Ohio and a Ford plant in Michigan — at the start of a strike that could expand to more locations.

The factories make Ford’s Bronco sport utility vehicle, GM’s Colorado and Canyon midsize trucks and Stellantis’ Jeep.

“This is our generation’s defining moment,” UAW president Shawn Fain said in a livestream on Thursday. “The money is there, the cause is righteous, the world is watching and the UAW is ready to stand up.”

The union is employing what it calls a “stand-up strike”, meaning individual locations will take part one by one, as a way to keep companies guessing. The term is a reference to the historic sit-down strike in the 1930s that helped form the UAW.

Brian Shepherd, the union’s chief organiser, said the option of strikes at all factories belonging to the three companies was “still on the table”.

GM and Stellantis said they were “disappointed” by the UAW’s leadership.

The strike comes at a time of increasing labour action across US industries. Writers and actors have walked out, pilot unions at major airlines won four-year contracts to raise pay by a third or more and United Parcel Service workers represented by the Teamsters achieved a wage increase of $7.50 an hour over five years.

Talks between the three Detroit carmakers and the UAW have been unusually contentious compared with other four-year cycles. Fain has adopted a confrontational approach, pointing out the billions of dollars in profits being made by the companies.

Another point of tension has been the automobile industry’s transition towards electric vehicles. The carmakers need billions of dollars to invest in plants and tooling to build battery-powered cars and trucks.

At the same time, they are forming EV battery joint ventures with non-unionised companies where workers are paid less than unionised counterparts. The UAW is seeking to ensure that industry jobs continue to be higher paid and unionised as the sector electrifies.

The UAW has lowered its demand for a wage increase to 36 per cent over four years, while the carmakers have raised their original offers to a range as high as 20 per cent. The UAW also wants to end the two-tier wage system in which newer workers take four years to reach the same pay as longtime employees, but carmakers have not agreed.

Ford chief executive Jim Farley said on CNBC on Thursday that if his company had agreed to the UAW’s request, “we would have lost $15bn and gone bankrupt by now”.

The company later said the UAW’s proposal “would more than double Ford’s UAW-related labour costs”.

A strike would potentially be a drag on the US economy and test the pro-union bona fides of President Joe Biden, especially in the battleground state of Michigan.

Oxford Economics estimated that if the three companies’ nearly 150,000 unionised workers eventually went on strike, the move could shut down roughly a third of US car production.

That would directly curtail US gross domestic product by as much as 0.3 per cent on an annualised basis, the consultancy said.

Still, the group’s lead US economist Michael Pearce said: “Any hit should be fully unwound once the dispute is over, so the impact on full-quarter GDP would likely be negligible.”