General Motors Corp. (GM), coinciding with its bankruptcy filing Monday, said it will shutter 17 factories and parts centers by the end of 2011. It will also cut an additional 5,000 salaried jobs.

The closures will reduce GM's U.S. facilities to 33 from 47 by 2012. Between 18,000 and 20,000 workers will be affected by the shutdowns, General Motors North America Manufacturing Vice President Tim Lee said during a conference call Monday. Employment reduction will be done according to terms in the United Auto Workers agreement.

The closures are expected to result in lower fixed costs per vehicle sold and more efficient capital investment. Plant efficiency is expected to jump with the reduction of the assembly plant count, Lee said.

Seven factories in Michigan and plants in Ohio, Indiana and Tennessee will be closed, the auto maker said in a statement. Two of the closures had been previously announced, including a castings factory in Massena, N.Y., which closed May 1.

Three of the facilities to close are parts centers and three factories could reopen if market demand rebounds.

The move was expected after GM cut a deal last month with the UAW as parts of its effort to smooth the company's path through bankruptcy.

Assembly plants targeted for closure are in Orion and Pontiac, Mich; Spring Hill, Tenn., and Wilmington, Del. Stamping plants in Grand Rapids and Pontiac, Mich.; Indianapolis, Ind.; and Mansfield, Ohio, will close. Powertrain factories in Livonia, Flint and Willow Run, Mich.; and Parma, Ohio, will close.

Lee said the company is still deciding where it will build its new small car announced last month. The contenders include the Orion, Mich.; Spring Hill, Tenn.; and Janesville, Wis. plants.

The re-tooled plant will be capable of building 160,000 cars annually and manufacture a combination of both small and compact vehicles.

"I would advocate that we make the decison quickly," Lee said.

The future of GM's Hummer production plant in Shreveport, La., hasn't yet been decided. GM intends to either end or sell off the brand. Production of GM's Traverse will be moved from Spring Hill to its Lansing, Mich., plant.

GM's service and parts division also announced it will cease operations and distribution centers in Boston; Columbus, Ohio; and Jacksonville, Fla. by Dec. 31, 2009.

-By Sharon Terlep; Dow Jones Newswires; sharon.terlep@dowjones.com