DaimlerChrysler AG's Chrysler said as many as 23 of its 32 North American auto and parts factories were briefly idled by power outages in an area covering New York, Toronto and Detroit. General Motors Corp and Ford Motor Co also said some plants were disrupted, without giving details.
Auto plants in Ontario run by Toyota Motor Corp and Honda Motor Co also were shut down by the power failure.
Detroit-based General Motors, the world's largest automaker, was "having a difficult time getting through" to some of its plants, spokesman Pat Morrissey said.
Dearborn, Michigan-based Ford was still compiling a list of affected plants, said spokeswoman Susan Bairley.
"The situation remains fluid, but we're getting reports of power returning at some facilities," Chrysler spokeswoman Debra Nelson said.
While the temporary plant disruptions affect tens of thousands of US and Canadian workers all the companies expect to quickly make up the lost production.
The blackouts began in Canada near Niagara Falls and cascaded along the Eastern Seaboard, leaving Wall Street without power and causing airlines to suspend flights in New York, Toronto, Detroit and Cleveland.
General Motors' Morrissey said that if the power failure "doesn't last too long, we won't have a problem making up any lost production."
Among Toyota's 10 North American auto and parts plants only its Cambridge, Ontario, factory, was affected by the power failures, spokeswoman Latondra Newton said.
The plant makes Corolla and Matrix small cars and will produce Lexus RX 330 sport- utility vehicles starting next month.
Honda, which operates 11 factories in the US, Canada and Mexico, said only its Alliston, Ontario, plant was idled.
"Alliston lines one and two were shut down after the first shift," Honda spokesman Ed Miller said.
Nissan Motor Co's vehicle and engine plants in Tennessee and Mississippi weren't affected by the outages, though its technical center in Farmington Hills, Michigan, was shut down by the power failure, Nissan's spokesman Scott Vazin said.
Some regional sales offices in Canada and the eastern US were also closed, Vazin said.