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.

United Parcel Service, Inc. (UPS) is an American multinational shipping & receiving and supply chain management company founded in 1907. Originally known as the American Messenger Company specializing in telegraphs, UPS has expanded to become a Fortune 500 company and one of the world's largest shipping couriers. UPS today is primarily known for its ground shipping services as well as the UPS Store, a retail chain which assists UPS shipments and provides tools for small businesses. UPS offers air shipping on an overnight or two-day basis and delivers to post office boxes through UPS Mail Innovations and UPS SurePost, two services that pass on packages to the United States Postal Service for last-mile delivery.