The plant, which assembles the Ford Crown Victoria and Mercury Grand Marquis models, normally operates two eight-hour shifts a day during the week.
"It's down today," said Lauren More, a spokeswoman for Ford Canada. "It's because of a material shortage due to the rail strike, so we are looking for alternatives in terms of trucking."
More said she could not predict when employees would be able to resume work given uncertainty about when the rail strike will end.
The plant in St. Thomas, which has about 2,578 employees, opened in 1967 and has been assembling the Crown Victoria and the Grand Marquis since 1984. It builds about 1,000 vehicles a day.
More than 2,000 Canadian conductors and switch yard workers at CN Rail, Canada's largest railway, walked of the job last Saturday in a contract dispute over a variety of issues including wages and working conditions.