For nearly 100 years, the major auto shows have cooperated even while competing, timing their events to make things easy on the automakers who spend millions of dollars getting displays, presentations, new vehicles and staff to the shows.

The pandemic has brought an end to that peace.

The country’s three major auto shows take place in New York, Detroit and Los Angeles. The first two canceled their 2020 shows early in the year, but the Los Angeles show refused to do so, holding out hope that because it was scheduled for November, the COVID-19 restrictions on large gatherings would be lifted by then.

Finally conceding that that’s not going to happen, organizers called off the L.A. show last week. And in the process, they dropped a bombshell.

The three car shows have had an unspoken agreement that they would space themselves about three months apart: New York in the spring, Detroit in summer and Los Angeles in fall. That gave automakers time to plan and stage their elaborate displays for each show. But instead of following suit, the Los Angeles show announced that it is scrapping its traditional date and instead moving to May.

“It’s an absurd decision. A declaration of war on the other shows,” said Paul Eisenstein, journalist, publisher of automotive website the Detroit Bureau and a veteran of news coverage at auto shows around the world.

A skirmish quickly broke out. The sponsors of the Detroit show announced that they’re moving their 2021 show to the fall.

“When word gets out, the organizers of the L.A. show are gonna say, ‘How the hell did we let this happen?’ ” said Larry Alexander, president of the Detroit Metro Convention and Visitors Bureau and chairman of the Detroit Regional Convention Center Authority, which runs TCF Center where the show takes place. “This is a great move for our city and region.”

Although no official response came from the automakers, the rescheduled Los Angeles show promised to be a logistical headache for them, Not only would packing up a show in New York, crossing the country to Los Angeles and then going back to Detroit be difficult, it would have messed up their usual practice of scheduling vehicle debuts from fall through early summer, depending on when the cars go on sale or are ready to be displayed.

“New vehicles debut throughout the year,” said Rod Alberts, executive director of the Detroit show. “The logic for shows is to spread out so manufacturers can introduce vehicles when they’re ready for debut or about to go on sale.”

Unlike other major auto shows, the Los Angeles one is privately owned. Other auto shows around the country are put on by local dealer associations, which see the events as part of their marketing strategy rather than a profit center. Local dealer groups also work closely with automakers to attract news-making executives, new vehicles and features.

(The Twin Cities Auto Show is sponsored by the Greater Metropolitan Automobile Dealers Association of Minnesota, an organization of about 130 dealers.)

The L.A. show issued a brief statement announcing the move and declined to answer questions.

The move could boomerang. The Los Angeles show generally is considered the least important of the big three. New York is a center for media companies, while Detroit is a hub of the global auto industry and generates much more press coverage than Los Angeles. The rescheduled Los Angeles show could find itself on the outside looking in.