"The United States Postal Service (USPS) is an
"independent establishment of the executive branch" of the United States Government (see 39 U.S.C. § 201) responsible for providing postal service in the United States. Within the United States, it is generally referred to as "the post office."
The USPS is often mistaken for a government-owned corporation (e.g. Amtrak), but as noted above is legally defined as an "independent establishment of the executive branch of the Government of the United States,"[cite this quote] as it is
wholly owned by the government and controlled by the Presidential appointees and the Postmaster General. As a quasi-governmental agency, it has many special privileges, including sovereign immunity, eminent domain powers, powers to negotiate postal treaties with foreign nations, and an exclusive legal right to deliver first-class and third-class mail."
United States Postal Service - Wikipedia, the free encyclopedia
clear as mud, huh?