The closure also ended an era in the city where GM Canada was born 91 years ago.
Bob Nesbitt, 67, who has worked at GM in Oshawa since 1964 and in the truck plant since 1971, drove a black GMC Sierra crew cab off the assembly line as hundreds of employees and retirees emotionally crowded around it, the Toronto Star reported.
PricewaterhouseCoopers LLP auto analyst Bill Pochiluk told the Star the closure will mean the loss of about 12,000 jobs, including the parts sector and service providers.
The award-winning plant, which employed about 1,000 workers on a single shift since the beginning of the year, employed about 3,500 at one time. It has sputtered in the last few years as fuel prices climbed and the truck market sagged, the Star said.
The company started in Oshawa in 1918 when the McLaughlin Carriage Co., which made horse-drawn carriages there since 1876, sold its interests to 10-year-old GM.
GM, now 101, announced the truck plant's closure, along with that of three other North American truck plants, last spring after gasoline prices spiked and the sale of large pickups collapsed.
GM still operates a large car assembly plant near the truck operation. It also has parts operations in St. Catharines, Ontario, in Canada's Niagara Region, and Windsor, Ontario, near Detroit. The Windsor plant, which builds transmissions, is set to close next year.