Thousands of members of the United Automobile Workers union went on strike Friday at three plants in three Midwestern states, the first strike to simultaneously affect three Detroit automakers.

The union and the companies — General Motors, Ford Motor and Stellar, Chrysler’s parent — were deadlocked in negotiations over a new collective bargaining agreement when the current contract expired at 11:59 p.m. Thursday.

As the deadline neared, workers began protesting at the targeted plants — in Michigan, Missouri and Ohio.

For starters, a strike would shut down one plant owned by each automaker and could force automakers to halt production elsewhere, shaking local economies in factory towns across the Midwest.

“We’re using a new strategy,” union president Sean Fine said in a video streamed via Facebook Thursday night. “We are calling on elected local people to stand up and join the strike.”

In its 88 years of existence, the union has called strikes targeting only one automaker, and a handful of companies have halted production for weeks. GM plants idled for 40 days in 2019 before the company and union agreed to a new contract.

The plants designated for Friday’s walkouts represent only a small fraction of all the unionized factories at GM, Ford and Stellantis and those companies’ 150,000 UAW members.

However, this limited strike could disrupt automakers as the sites produce highly profitable trucks such as the Ford Bronco sport utility vehicle and the Chevrolet Colorado pickup. If contractual agreements remain elusive, the walkout will widen, Mr. Fine clarified.

“It’s certainly a different approach, and Fine is talking tough and has tough proposals,” said Dennis Devaney, a former member of the National Labor Relations Board who is a labor attorney in Detroit.

Affected plants include a GM plant in Wentzville, Mo., which makes the GMC Canyon and Colorado, and the Stellandis complex in Toledo, Ohio, which makes the Jeep Gladiator and Wrangler. At Ford’s Michigan assembly plant in Wayne, where the Bronco is built along with the Ranger pickup, only workers walk out of the assembly area and paint shop, Mr. Fine said.

According to the union, the GM plant employs 3,600 hourly workers and the Stellandis plant employs 5,800. The union said about 3,300 workers at Ford’s Michigan assembly plant would be affected.

The union has demanded a 40 percent pay increase over the next four years, pointing out that compensation packages for the three companies’ chief executives have increased by that much on average over the past four years.

Mr. who was sworn in as the union president this year. Fein has called for wage increases in response to inflation, shorter work weeks, retiree pensions and cost-of-living adjustments in response to job protection measures such as health care and skills. Attack the plants designated for closure. In addition, he wants changes to the starting wage rate that would start new workers at about $17 an hour and take eight years for them to reach the UAW’s top wage of $32 an hour.

So far, manufacturers Mr. Fine was met with half his salary, but resisted all other demands.

On Thursday, GM said its latest offer included a 20 percent wage increase over the life of the new contract, a 10 percent raise in the first year, and cost-of-living adjustments, but only for more senior workers. GM also said it would allow new hires to reach higher wages after four years on the job.

“We are presenting a compelling and unprecedented offer,” said GM Chief Executive Mary D. Parra said in a video posted on a company website Thursday night. “What you told us is most important: wage growth, job security and long-term stability.”

He also suggested meeting most or all of the union’s demands could hurt the company’s prospects because it has invested billions of dollars in transitioning to electric vehicles.

“We are at a crossroads in our path to transform the company,” he said. “Make no mistake: If we don’t continue to invest, we will lose ground, and it will happen fast. No one wins a strike.

Ford and Stellantis also made new proposals to the union 48 hours before the deadline but did not disclose details.

Biden Administration On Thursday, President Biden said Mr. It said it had spoken to Fine and auto company leaders about the status of negotiations. A senior White House official, Mr. Biden didn’t press the companies or the union on specifics, but said he encourages all parties to be at the table and make sure workers get a fair deal.

The union’s demands for significantly higher wages and new benefits are a sharp departure from the past 20 years, when automakers were ailing and the UAW was forced to accept huge concessions to help companies survive.

But lately, GM, Ford and Stellantis have been posting near-record earnings. In the first half of the year, Ford earned $3.7 billion and GM $5 billion. Stellandis posted a profit of 11 billion euros (about $11.9 billion).

Having worked as an electrician at Chrysler and working in union management, Mr.

In speeches to union members, he often highlighted the pay of automakers’ chief executives. Last year, Ms. Barra took home $29 million. Ford’s Jim Farley earned $21 million, while Stellandis president Carlos Tavares was awarded a package worth about $25 million.

An extended strike could reduce the availability of new cars and raise prices. A prolonged strike would ripple through the automaker’s supply chain and hurt other businesses as workers live on $500 a week in strike pay from the union.

The auto industry is still dealing with the lingering effects of the pandemic. After the impact of the coronavirus, production was halted, and the supply of vehicles fell sharply Domestic car consignments At the end of 2019, the stake was a quarter.

Michael D. Sheer Contributed report.