General Motors Corp. says 18,657 workers have elected to take buyout or other retirement incentives to leave the auto maker, bringing the number of blue-collar departures over the last two years to more than 53,000.

GM first announced last month that it would pay 19,000 workers to leave. The employees were given a month to change their minds.

The latest attrition program will trim GM’s hourly payroll to 55,743, although the auto maker recently began hiring new employees at a lower wage rate as part of concessions it won from the United Auto Workers union during contract negotiations last year.

New hires performing non-core functions, such as material handling, receive a second-tier wage of roughly $14 excluding benefits. Current UAW-represented employees earn twice that.

GM spokesman Tony Sapienza says the new hires make it difficult to peg an exact number on the auto maker’s hourly payroll. “It’s a moving number.”

The 18,657 departures include 1,259 retroactive employees, who retired before the program began but were grandfathered as part of GM’s new 4-year labor agreement with the UAW.

The number falls near the 20,000 mark GM expected and ahead of the 15,000 the union anticipated.

Nearly half of the departures come from GM sites in job-weary Michigan, including some 2,000 workers from truck-centric assembly plants in Flint and Pontiac. Another 1,352 workers at SUV plants in Janesville, WI, and Moraine, OH, also took buyouts.

Due to a rapid shift this year in consumer demand away from pickups and SUVs to more economical passenger cars and cross/utility vehicles, GM announced earlier this month it would close Janesville, Moraine and truck plants in Oshawa, ON, Canada, and Toluca, Mexico.