HOLMES MILL, Ky.—The U.S. Postal Service plays two roles in America: an agency that keeps rural areas linked to the rest of the nation, and one that loses a lot of money.

Now, with the red ink showing no sign of stopping, the postal service is hoping to ramp up a cost-cutting program that is already eliciting yelps of pain around the country. Beginning in March, the agency will start the process of closing as many as 2,000 post offices, on top of the 491 it said it would close starting at the end of last year. In addition, it is reviewing another 16,000—half of the nation's existing post offices—that are operating at a deficit, and lobbying Congress to allow it to change the law so it can close the most unprofitable among them. The law currently allows the postal service to close post offices only for maintenance problems, lease expirations or other reasons that don't include profitability.

The postal service argues that its network of some 32,000 brick-and-mortar post offices, many built in the horse-and-buggy days, is outmoded in an era when people are more mobile, often pay bills online and text or email rather than put pen to paper. It also wants post offices to be profitable to help it overcome record $8.5 billion in losses in fiscal year 2010.

A disproportionate number of the thousands of post offices under review are in rural or smaller suburban areas, though the postal service declined to provide any estimate on how many beyond those slated to begin closure in March might ultimately close or which ones are being targeted. "We want to make the smartest decisions possible with the smallest impact on communities," Dean Granholm, vice president for delivery and post office operations, said in an interview. He said the agency is identifying locations that are operating at a deficit and looking "for the opportunity to start the process of closing."