"...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.[5] 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.[..."
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