In 2007 and 2008, the Postal Service lost $7.9 billion, USA Today reported Tuesday.
Recently, the USPS asked Congress to cut deliveries down to five days a week from the current six-day schedule.
"We have to make adjustments quickly to keep the ship afloat," Postmaster General John Potter said. "We have to weather the storm of the bad economy first and figure out how traditional mail fits into an electronic world," he said.
Among the largest expenses for the Postal Service is healthcare for employees. The service's $53 billion in healthcare obligations is larger than the same line item for General Motors Corp., Ford Motor Co. and Chrysler LLC combined, the newspaper said.
By law, the service is supposed to break even. However, it is on track to run out of cash at the end of September, when a $5.4 billion retiree health fund payment is due, the newspaper said.
"The last thing we want to do is not be able to make payroll and provide service to the American people," Potter said.