OSHAWA, Ontario — General Motors has been making cars in Oshawa, Ontario, for more than a century in factories that once employed upward of 40,000 people, so the company’s announcement on Monday that it would stop production brought recriminations from across the Canadian political spectrum.

But for Eva McKeen, an inspector in the paint shop that looms over the north end of the vast manufacturing complex, the pain and the sense of betrayal went far beyond political and economic arguments.

“Just as you’re getting older to know that you don’t have a job, it’s really heart-wrenching,” she said.

Ms. McKeen was among the hundreds of workers who walked out of the plant in protest just before managers were about to announce its death sentence. Outside, they began waving red flags while blockading the complex’s truck entrances. The ponchos they wore, bearing the logo of their union, Unifor, offered scant protection against the sleet coming down.