Article I, Section 8, Clause 7 of the United States Constitution, known as the Postal Clause or the Postal Power, empowers Congress "To establish Post Offices and post Roads".
The Postal Clause was added to the Constitution to facilitate interstate communication as well as to create a source of revenue for the early United States. There were some early disagreements as to the boundaries of the Postal Power. John Jay, in a letter to George Washington, opined that the postal service should not be burdened with the responsibility for handling newspaper delivery, and also suggested that the Post Office be placed under the supervision of the executive branch (a suggestion which later led to the creation of the Post Office Department).Thomas Jefferson feared that the postal service would become a source of patronage and a waste of money. Jefferson also expressed doubt at granting Congress the power to designate post roads, as he considered road building to be a state responsibility.
The Clause has been construed to give Congress the enumerated power to designate mail routes and construct or designate post offices, with the implied authority to carry, deliver, and regulate the mails of the United States as a whole. An early controversy was whether Congress had the power to actually build post roads and post offices, or merely designate which lands and roads were to be used for this purpose, and to what extent that power could be delegated to the Postmaster General. The U.S. Supreme Court construed the power narrowly during the early part of the 19th century, holding that the power consisted mostly of designation of roads and sites, but gradually gave way later on, allowing appropriation of land for postal purposes.