Although the United States Postal Service operates like a private business, it is a branch of the federal government. A board of governors and the Postmaster General head the USPS with the assistance of the Postal Regulatory Commission. Final authority over the Postal Service rests with Congress.
According to the Cato Institute's Downsizing the Federal Government website, the USPS operates on revenues from the sales of its products, such as stamps, packaging materials and envelopes, as well as its services, including overnight delivery. Despite being owned by the federal government, the organization does not receive federal appropriations. After Wal-Mart, a private corporation, the USPS is the second-largest employer in the United States. The USPS is required by statute to offer mail service to all Americans regardless of where they live or what it costs to provide the service. Since the advent of email and other forms of electronic communication, the Postal Service has experienced steadily declining revenues.
On its official website, the USPS notes that it was transformed into an independent establishment of the federal government's executive branch in 1971. At that time the Postmaster General was no longer considered part of the president's Cabinet. Although the structure of the entity changed that year, its mission of serving all Americans with basic mail delivery remained the same.