Two Canadian sedan-assembly lines were closed as the result of the strike against the automaker that reverberated in Canada.
GM Canada idled the No. 1 car assembly plant at its complex in Oshawa, east of Toronto, at 3 a.m. EDT (0700 GMT). The lack of key major components from the United States halted work at the No. 2 line with the end of the day shift at 2:30 p.m. (1830 GMT).
"The car plant will be down until the strike is resolved," GM Canada spokesman Stew Low said.
About 5,600 people work on those two lines, making the Chevrolet Impala and Monte Carlo, Pontiac Grand Prix and Buick Allure.
Canadian Auto Workers president Buzz Hargrove estimates 80,000 to 100,000 Canadians, mostly in Ontario, could be laid off by the end of the week at GM Canada, its parts suppliers and other companies dependent on the industry.
Carlos Gomes, auto-sector economist at the Bank of Nova Scotia, said that "certainly somewhere around the 80,000 range might be a reasonable number."
The Oshawa pickup-truck plant, with 3,900 employees, remains at work on three shifts and is believed to have enough parts to keep operating until at least Thursday, though Low declined to be specific.
GM's transmission factory in Windsor, Ontario, employing 1,300, closed shortly after the U.S. strike began Monday, and a 2,500-employee power-train-component plant in St. Catharines, Ontario, looked set to be idle by the weekend.
The CAMI plant, a 2,700-worker GM-Suzuki joint venture in Ingersoll, Ontario, which makes Pontiac Torrent and Chevrolet Equinox crossovers, "just happens to be down on a one-week inventory adjustment, so there's no impact on them this week," Low said.
Laid-off GM Canada unionized workers face a week without income before qualifying for Employment Insurance benefits and a supplementary payout, totalling 65 percent of their usual pay. Many others in the sector stand to be more harshly affected.
The effect on the parts industry depends on how long the strike lasts, observed Ed Frackowiak, CEO of Wescast Industries Inc.
"If it continues beyond a week or two, then of course it's going to have an impact," said Frackowiak, whose Brantford-based company does more than one-quarter of its business with GM.
"If they get things resolved, then I think we're going to be OK."