After more than a century and 20 million autos, the General Motors Co. plant in Oshawa, Ontario will make its last vehicle Wednesday when a final pickup truck rolls off the line.

Oshawa’s auto-making roots go back to 1867, the year of Canada’s Confederation, and the founding of a carriage company by the McLaughlin family. GM has been producing vehicles at the plant since 1918, making it the company’s oldest existing assembly plant.

The business survived two world wars and the Depression, and grew into one of the world’s largest auto-manufacturing facilities with tens of thousands of employees. It even survived GM’s bankruptcy. But the Oshawa assembly plant could not weather two other inexorable forces: the emergence of low-wage Mexico as an auto-making powerhouse and GM’s bet on electric vehicles.

The shutdown of Oshawa assembly is part of a reorganization that trims excess production as auto sales soften and GM shifts resources to focus on electric and autonomous vehicles. The overhaul cut a net 11,000 workers across the company. The Oshawa plant had been making Chevrolet Silverado and GMC Sierra pickups.

Starting next year, the site will be used for parts manufacturing and a test track for advanced technology vehicles. Of the roughly 2,200 employees GM says are affected, 1,600 are taking buyout packages, including 1,200 who will retire on defined benefit pensions, giving them a guaranteed income for life.

About 300 employees will be able to work at the new operations and about 100 have transferred to GM facilities elsewhere in Ontario. Two hundred are hoping to be recalled, either in Oshawa or elsewhere in Ontario, and will receive layoff benefits in the meantime, according to Jennifer Wright, a spokeswoman with GM Canada.

A group of workers is lobbying the government to take over the plant and convert it to electric-vehicle production. The employment losses rise to about 5,000 when hundreds of temporary part-time workers are taken into account, along with over 1,000 outsourced GM jobs, and more than 1,000 supplier jobs, according to Tony Leah, a spokesman for Green Jobs Oshawa and chairman of the political action committee for Unifor Local 222.

For its part, GM says the creation of an autonomous testing track -- named after Colonel Sam McLaughlin -- will continue the company’s legacy in Oshawa. The automaker is also boosting its headcount of software engineers in Markham, Ontario, about 50 kilometers (30 miles) to the west of Oshawa.

--With assistance from David Welch

A look back at GM's history in Canada

For generations, the face of General Motors in Oshawa, Ont., was its most prominent resident: Sam McLaughlin. Sam and his older brother George helped build the company their father founded in 1867 into the McLaughlin Carriage Works, the largest carriage maker in the British Empire. In 1908 it transitioned into McLaughlin Motor Car Co., and General Motors bought it a decade later. Sam stayed on, serving as president of GM Canada for 27 years and chairman of the board from 1945 until his death in 1972. Bloomberg News' Danielle Bochove has more on GM's history in Canada and how it has evolved to where it is today.