DETROIT (TNS) — General Motors will close three assembly plants by the end of 2019, it said Monday, including Detroit-Hamtramck in Michigan, Lordstown in Ohio and Oshawa in Ontario.

More than 6,200 jobs are at stake: roughly 1,500 in Hamtramck; 1,600 in Lordstown; about 2,500 in Oshawa; and a total of 645 at transmission plants in Warren in suburban Detroit and near Baltimore.

The Hamtramck plant makes the Chevrolet Volt and Impala, the Cadillac CT6 and the Buick LaCrosse. Those vehicles and other cars made at the targeted facilities will be terminated.

In addition to the production cuts, GM said it will reduce its North American white-collar workforce by about 8,000. The deadline passed last week on a voluntary buyout for those workers, and GM spokesman Pat Morrissey told the Free Press that only 2,250 employees have asked to take the offer, meaning as many as 5,750 workers could be cut if the company keeps to its announced total. Analysts told the Free Press to expect involuntary cuts in January.

The company said it would save $6 billion by the end of 2020.

Morrissey said most of the U.S.-based production workers will have a chance to relocate to another GM plant. GM's heavy-duty truck plant in Flint will be ramping up production and will need workers. Also, GM's Arlington, Texas, plant where it builds its full-size SUVs, is ramping up to build the next-generation Chevrolet Tahoe, Chevrolet Suburban, Suburban XL and GMC Yukon.

The company also confirmed it will add a third vehicle next year to its production lineup at its plant in Spring Hill, Tenn.

A future Cadillac crossover will be produced in Spring Hill, GM spokeswoman Courtney Jackson said Monday. The underused plant already produces the crossover Cadillac XT5 and GMC Acadia midsize SUV.

"GM is continuing to take proactive steps to improve overall business performance, including the reorganization of its global product development staffs, the realignment of its manufacturing capacity and a reduction of salaried workforce," the company said in a news release Monday.