The U.S. Postal Service, which predicts an annual loss of $18.2 billion by 2015, plans to eliminate 5.4 percent of its workforce by closing almost half of its mail-processing facilities to cut costs.

The service plans to shut 223 of its 461 mail-processing plants by February 2013, Postmaster General Patrick Donahoe said in a telephone interview today. The closings will cut about 35,000 jobs, said David Partenheimer, a Postal Service spokesman.

The closings will save the Washington-based service about $2.5 billion a year, Donahoe said. In September, the agency said it was seeking to save $3 billion a year by closing 252 plants and cutting 35,000 jobs.