NASHVILLE (AP) - The U.S. Postal Service says it is closing three mail processing operations in Tennessee.

The agency announced on Thursday it would shut down processing centers in Chattanooga, Jackson, and Johnson City.

Work from Chattanooga will be moved to the processing and distribution centers in Nashville and Atlanta. Mail now handled in Jackson will flow to the Memphis center. The Johnson City work will move to Knoxville.

Specific dates for the transitions haven't been decided.

The Postal Service says first-class mail volume has declined 25 percent since 2006. The agency relies on the sale of postage, postal product and services for all of its income.