The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an independent agency of the executive branch of the United States federal government responsible for providing postal service in the United States, its insular areas, and its associated states. It is one of the few government agencies explicitly authorized by the Constitution of the United States. As of 2023, the USPS has 525,469 career employees and 114,623 non-career employees.

In the United States government, independent agencies are agencies that exist outside the federal executive departments and the Executive Office of the President. In a narrower sense, the term refers only to those independent agencies that, while considered part of the executive branch, have regulatory or rulemaking authority and are insulated from presidential control, usually because the president's power to dismiss the agency head or a member is limited.